v1.11.1 - update ZoneInfoBroker::targetZoneInfo(); no functional change

• 1.11.1 (2022-02-16, TZDB 2021e)
  • Update ZoneInfoBroker::targetZoneInfo() to return a ZoneInfoBroker
    instead of a raw ZoneInfo* pointer.
    • Internal wiring change, no change to external API.
    • Allows alternative ZoneInfoBroker classes to implement a consistent
      API.

v1.11.0 - change Link timezones from hard links to symbolic links

• 1.11.0 (2022-02-14, TZDB 2021e)
  • Regenerate zonedb/ and zonedbx/ using latest AceTimeTool which
    identifies notable Zones and Policies whose DST shifts are not exactly
    0:00 or 1:00. No actual data change. Notable policies relevant from 2000
    until 2050 are:
    • ZonePolicy Eire: DST shift -1:00
    • ZonePolicy LH: DST shift 0:30
    • ZonePolicy Morocco: DST shift -1:00
    • ZonePolicy Namibia: DST shift -1:00
    • ZonePolicy StJohns: DST shift 2:00
    • ZonePolicy Troll: DST shift 2:00
  • Add support for overflow and underflow to TimePeriod.
    • When isError() returns true, the sign() method discriminates
      3 error conditions, and the printTo() prints the following:
      • 0: generic error, ""
      • +1: overflow, "<+Inf>"
      • -1: underflow, "<-Inf>"
      • See USER_GUIDE.md#TimePeriod.
  • Change Link entries from "hard links" to "symbolic links".
    • This allows a TimeZone object to know whether it is a Zone entry
      or a Link entry.
    • Add TimeZone::isLink() and ZoneProcessor::isLink() methods.
    • Add bool followLink = true parameter to various other methods
      (getZoneId(), printTo(), printShortTo()) which determines
      whether the method resolves to the current Link entry or follows the
      link to the destination Zone entry.
    • MemoryBenchmark says that this increases
      flash consumption by 100-300 bytes, due to the extra code needed to
      follow the symlink. But the ability to determine whether the TimeZone
      is a link or not will be necessary for an upcoming feature, so this
      slight increase in flash consumption seems worth it.
    • Regenerate zonedb/ and zonedbx to convert Link entries from
      hard links to symbolic links.
    • See Symbolic Links for more info.
  • Add offset_date_time_mutation methods.
    • Similar to zoned_date_time_mutation methods.
    • Provides some convenient mutation methods for OffsetDateTime.
  • Upgrade Arduino CLI from 0.19.2 to 0.20.2.

v1.10.0 - add 'fold' to control DST gaps and overlaps; add more docs and examples for ESP8266 and ESP32

• 1.10.0 (2022-01-18, TZDB 2021e)
  • MemoryBenchmark: Add memory consumption for ZoneSorterByName and
    ZoneSorterByOffsetAndName.
    • AVR: 180-530 bytes of flash
    • 32-bit: 120-600 bytes of flash
  • Rename internal TransitionStorage::findTransition() to
    findTransitionForSeconds() for better self-documentation.
  • Move third party SAMD21 boards to new Tier 3 (May work, but not supported)
    level.
    • I can no longer upload binaries to these boards using Arduino IDE
      1.8.19 and SparkFun SAMD Core 1.8.6.
  • Add support for fold parameter to control behavior around DST gaps
    and overlaps.
    • The semantics of the fold parameter is intended to be identical to
      Python PEP 495.
    • Add LocalTime::fold(), LocalDateTime::fold(),
      OffsetDateTime::fold(), ZonedDateTime::fold().
    • Update ExtendedZoneProcessor::getOffsetDateTime(acetime_t) to
      calculate the OffsetDateTime::fold() as an output parameter.
    • Update ExtendedZoneProcessor::getOffsetDateTime(const LocalDateTime&) to handle LocalDateTime::fold() as an input
      parameter.
    • Increases flash usage of ExtendedZoneProcessor by around 600 bytes
      on AVR, and 400-600 bytes on 32-bit processors.
  • Add toUnixSeconds64() and forUnixSeconds64() methods to
    LocalDate, LocalDateTime, OffsetDateTime, ZonedDateTime.
    • These use 64-bit int64_t integers, which allows Unix seconds to be
      used up to 2068-01-19T03:14:07Z (which is the limit of these
      various classes due to the internal use of 32-bit acetime_t).
    • These methods make it easier to interoperate with the time_t typedef
      for int64_t on the ESP8266 and ESP32 platforms.
  • Add EspTime app that shows how to integrate
    the SNTP client on the ESP8266 and ESP32 platforms with AceTime.

v1.9.0 - allow sorting of zones by name or offset-name; reduce flash by 1100-1300 bytes on AVR

• 1.9.0 (2021-12-02, TZDB 2021e)
  • Add ZoneSorterByName and ZoneSorterByOffsetAndName classes
    to sort zone indexes, ids, or names according to 2 pre-defined sorting
    criteria: (1) by name, or (2) by UTC offset and then by name.
    • See the Zone Sorting section in the
      USER_GUIDE.md.
    • Adds a new dependency to
      AceSorting library.
  • Add examples/CompareAceTimeToHinnantDate to compare the performance of
    AceTime compared to Hinnant date library.
    • AceTime seems to be about 90X faster for converting date-time
      components to epoch seconds.
  • Add MaxBufSize comment field into zonedb[x]/zone_infos.h which is the
    maximum over all zones in that file. Must be less than or equal to
    ExtendedZoneProcessor::kMaxTransitions.
  • Potential Breaking Change: class TransitionStorage
    • Rename getHighWater() to getAllocSize(). This now returns the
      maximum number of transitions that has been allocated so far, which
      happens to be getHighWater() + 1.
    • Rename resetHighWater() to resetAllocSize().
    • Rename ExtendedZoneProcessor::resetTransitionHighWater() to
      resetTransitionAllocSize().
    • All of these methods were intended for internal debugging so these
      changes are not considered to be an API change.
    • The semantics of these methods are now closer to the algorithm in
      AceTimePython/zone_processor.ZoneProcessor.
  • Breaking Change: Extract BasicZoneProcessorCache and
    ExtendedZoneProcessorCache out of BasicZoneManager and
    ExtendedZoneManager. Remove all pure virtual methods from
    ZoneManager, making the class hierarchy non-polymorphic.
    • Saves 1100-1300 bytes of flash on AVR processors.
    • See Migrating to v1.9 for
      migration info.
  • Breaking Change: Remove pure virtual methods from LinkManager,
    analogous to their removal from ZoneManager.
    • Saves 68 bytes of flash on AVR processors.
    • See Migrating to v1.9 for
      migration info.

v1.8.2 - upgrade to TZDB 2021e

• 1.8.2 (2021-10-28, TZDB 2021e)
  • Update to TZDB 2021e.
    • https://mm.icann.org/pipermail/tz-announce/2021-October/000069.html
    • Palestine will fall back 10-29 (not 10-30) at 01:00.

v1.8.1 - upgrade to TZDB 2021d

• 1.8.1 (2021-10-18, TZDB 2021d)
  • Add make -C examples/MemoryBenchmark epoxy to GitHub actions.
  • Upgrade to TZDB 2021d.

v1.8.0 - extract Clocks to AceTimeClock; replace Wire.h with AceWire.h; extract thin links to LinkManagers

• 1.8.0 (2021-10-15, TZDB 2021c)
  • Breaking Change: Move clock classes under ace_time::clock and
    implementation classes under ace_time::hw to the new
    AceTimeClock repo.
    • Classes remain in the same C++ namespace.
    • Client code needs to add #include <AceTimeClock.h>.
    • See Migrating to v1.8 for
      migration info.
  • Breaking Change: Convert DS3231.h into a template class with an
    indirect dependency to <AceWire.h>, replacing direct dependency on
    <Wire.h>.
    • Just including the <Wire.h> header causes flash memory to be
      consumed, even if Wire object is never used.
    • Saves 1000-1500 bytes of flash on AVR, and up to 4000 bytes on STM32.
    • See Migrating to v1.8 for
      migration info.
  • Breaking Change: Extract thin link functionality from
    BasicZoneManager and ExtendedZoneManager into new BasicLinkManager
    and ExtendedLinkManager.
    • Saves 200-500 bytes of flash memory if the feature is not used.
    • Client application can determine whether to pay for this
      functionality, instead of automatically being included into the
      ZoneManager.
    • See the Thin Links section in the User
      Guide and Migrating to v1.8 for
      migration info.
  • Simplify documentation
    • Merge docs/installation.md into README.md.
    • Move docs/date_time_timezone.md to USER_GUIDE.md.
    • Remove docs/clock_system_clock.md after migrating it to
      the AceTimeClock project.
    • Merge docs/comparisons.md into README.md.

v1.7.5 - upgrade to TZDB 2021c; fix edge case bug when Transition occurs at ZoneEra transition

• 1.7.5 (2021-10-06, TZDB 2021c)
  • Bug Fix: Update ExtendedZoneProcessor.h to implement better
    detection of Transitions that occur at the exact same time as the switch
    to a different ZoneEra.
    • They are now considered to happen at the same time if any of the 'w'
      time, 's' time, or 'u' time are equal.
    • The behavior of ExtendedZoneProcessor.h should now be identical
      to zone_processor.py in the AceTimePython library.
    • Seems to affect only Europe/Lisbon in 1992, which is not a part of
      the predefined zonedb or zonedbx database, which normally include
      only 2000 until 2050.
  • Testing
    • Create AceTimePython
      library extracted from the previously split
      AceTimeTools project.
    • Update ace_time/testing/ExtendedTransitionTest.h to validate
      the exact equality between the observed maximum buffer size of
      TransitionStorage as observed by ExtendedZoneProcessor and the
      buffer size calculated by AceTimeTools using zone_processor.py of
      AceTimePython library.
    • Create examples/DebugZoneProcessor for debugging the internal logic
      of ExtendedZoneProcessor.
  • Tool Chain
    • Upgrade ESP8266 Core from 2.7.4 to 3.0.2.
      • Flash consumption increases by 3-5 kB across the boad.
    • Upgrade Arduino CLI from 0.19.1 to 0.19.2.
    • Upgrade Arduino IDE from 1.8.13 to 1.8.16.
    • Upgrade Teensyduino from 1.54 to 1.55.
    • Upgrade SparkFun SAMD Core from 1.8.3 to 1.8.4.
  • TZDB Upgrade TZDB from 2021a to 2021c.
    • TZDB 2021b is skipped because of controversial changes which were
      reverted in 2021c.
    • 2021c announcement:
      https://mm.icann.org/pipermail/tz-announce/2021-October/000067.html
    • 2021b announcement:
      https://mm.icann.org/pipermail/tz-announce/2021-September/000066.html
    • Jordan now starts DST on February's last Thursday.
    • Samoa no longer observes DST.
    • 10 Zones from 2021a were converted to Links:
      • Africa/Accra -> Africa/Abidjan
      • America/Atikokan -> America/Panama
      • America/Blanc-Sablon -> America/Puerto_Rico
      • America/Creston -> America/Phoenix
      • America/Curacao -> America/Puerto_Rico
      • America/Nassau -> America/Toronto
      • America/Port_of_Spain -> America/Puerto_Rico
      • Antarctica/DumontDUrville -> Pacific/Port_Moresby
      • Antarctica/Syowa -> Asia/Riyadh
      • Pacific/Enderbury -> Pacific/Kanton
    • 1 new Zone was created:
      • Pacific/Kanton
    • BasicZoneManager now supports 258 Zones and 193 Links using the
      zonedb database
    • ExtendedZoneManager now supports 377 Zones and 217 Links using the
      zonedbx database

v1.7.4 - move tools and validation tests into separate projects

• 1.7.4 (2021-08-26)
  • Move ./tools directory into new
    AceTimeTool repo.
  • Move ./tests/validation directory into new
    AceTimeValidation repo.
    • Update .github/workflows/validation.yml to use AceTimeValidation
      instead of ./tests/validation.
  • This is a maintenance release. No changes to the core library code.

1.7.3 - fix broken documentation links; maintenance release before major refactoring

• 1.7.3 (2021-08-25)
  • Fix numerous broken links in documents moved to docs/*.md in an earlier
    refactoring.
  • Add experimental DS3231Module class that uses AceWire library.
  • This is a maintenance release before some major refactoring. No changes to
    core library code.