0.6 - simplify Clock classes

• 0.6
  • Update tests to use UnixHostDuino.
  • Fix broken restore functionality in CommandLineClock. Make it work
    on Unix using UnixHostDuino. Make it work on ESP8266 and ESP32 again.
  • Update flash memory consumption numbers in zonedb/zone_infos.cpp and
    zonedbx/zone_infos.cpp.
  • Lift ace_time::common::DateStrings to just ace_time::DateStrings
    because it was the only data/time class in the common:: namespace so
    it seemed inconsistent and out of place.
  • Breaking Change Large refactoring and simplification of the
    ace_time::clock classes. Merged TimeKeeper and TimeProvider into a
    single Clock class hierarcy. Merged SystemClockSyncLoop (separate
    class) into SystemClockLoop (subclass of SystemClock) and
    SystemClockSyncCoroutine (separate class) into SystemClockCoroutine
    (subclass of SystemClock with mixin of ace_routine::Coroutine). Merged
    keepAlive() into ::loop() and ::runCoroutine() methods, so we don't
    need to worry about it separately anymore. Made SystemClockLoop use the
    non-blocking methods of Clock, making it as responsive as
    SystemClockCoroutine.
  • Add UnixClock.h which provides access to the internal Unix clock
    when using UnixHostDuino.

v0.5.2 - support ATmega2560; pack zoneinfo files to save 2.5 - 6 kB of flash

• 0.5.2
  • Create HelloZoneManager and add it to the README.md.
  • Recommend using "Arduino MKR ZERO" board or "SparkFun SAMD21 Mini
    Breakout" board for the "SAMD21 M0 Mini" boards.
  • Pack basic::ZoneInfo, extended:ZoneInfo and related structs tighter on
    32-bit processors, saving 2.5kB on the Basic zoneinfo files and 5.6kB on
    Extended zoneinfo files.
  • Pack basic::Transition and extended::Transition tighter on 32-bit
    processors, saving 20-32 bytes on BasicZoneProcessor and
    ExtendedZoneProcessor.
  • Test and support ATmega2560 AVR processor.
  • Replace all uses of Serial with SERIAL_PORT_MONITOR for compatibility
    with boards (e.g. SAMD boards) which use SerialUSB as the serial
    monitor.

0.5.1 - Support SAMD21 boards

• 0.5.1 (2019-07-24, TZ DB version 2019a, beta)
  • Add documentation about the ZoneManager into USER_GUIDE.md.
  • Move DateStrings string pointers into PROGMEM, saving 42 bytes of RAM.
  • Use SERIAL_PORT_MONITOR instead of Serial everywhere for portability
    across different Arduino boards.
  • Support SAMD21 boards except for EEPROM which SAMD21 does not support.

0.5 - ZoneManager allows dynamic creation of TimeZone

• 0.5 (2019-07-21, TB DB version 2019a, beta)
  • Remove over-engineered SystemClockHeartbeatLoop and
    SystemClockHeartbeatLoop and replace with just a call to
    SystemClock::keepAlive().
  • Remove overly complex ManualZoneProcessor and merge most of its
    functionality directly into the TimeZone using kTypeManual. We lose
    the manual abbreviations provided by ManualZoneProcessor but the
    simplification of using just the TimeZone object without an extra object
    seems worth it.
  • Add a stable zoneId to ZoneInfo that identifies a zone. It is
    formed using a hash of the fully qualified zone name. The
    tzcompiler.py generator script will detect hash collisions and create an
    alternate hash.
  • Rename old ZoneManager as the ZoneRegistrar, and
    repurpose ZoneManager as the TimeZone factory, which keeps an internal
    cache of ZoneProcessor. TimeZone objects can be dynamically bound to
    ZoneProcessor objects using createForZoneInfo(),
    createForZoneName(), `createForZoneId().
  • Add TimeZoneData data struct to allow serialization of a TimeZone object
    as a zoneId so that it can be reconstructed using
    ZoneManger::createForTimeZoneData().
  • Rename ZoneSpecifier to ZoneProcessor to describe its functionality
    better. ZoneInfo is now passed directly into the TimeZone object using
    the TimeZone::forZoneInfo() factory method, with the ZoneProcessor
    acting as a helper object.

0.4 - store zoneinfo files in PROGMEM

• 0.4 (2019-07-09, TZ DB version 2019a, beta)
  • Support the less-than-or-equal syntax {dayOfWeek}<={dayOfMonth}
    appearing in version 2019b of the TZ Database which contains Rule Zion, 2005 to 20012, IN Apr, ON Fri<=1.
  • Add BasicZoneManager and ExtendedZoneManager to retrieve ZoneInfo
    from TZ Database string identifier (e.g. "America/Los_Angeles").
  • Add configuration options (ACE_TIME_USE_BASIC_PROGMEM and
    ACE_TIME_USE_EXTENDED_PROGMEM) to place zoneinfo
    files into PROGMEM to save static RAM.

0.3.1 - add copyright notices to source files

• 0.3.1 (2019-06-30, beta)
  • Add copyright notices on source files.
  • Fix typos and formatting of README.md and USER_GUIDE.md.
  • No functional change from 0.3.

0.3 - support Link entries from TZ Database

• 0.3 (2019-06-28, beta)
  • Support Link entries from TZ Database files as C++ references to
    corresponding Zone entries.
  • Add backward and etctera files from TZ Database to the tzcompiler.py
    processing. ExtendedZoneSpecifier now supports every Zone and Link
    entry in the TZ Database (except those in backzone and systemv).
  • Add better zone and link name normalization. Convert + into _PLUS_,
    all other non-alphanumeric (0-9a-zA-Z_) converted to underscore _.
  • Move validation unit tests into separate tests/validation directory.
    Use Makefiles to generate validation_data.* files dynamically at compile
    time.

0.2 - better handling of gaps and overlaps in wall time with some date normalization

• 0.2 (2019-06-26, alpha)
  • Reduce flash memory size of WorldClock by removing extra font.
  • Split USER_GUIDE.md from README.md.
  • Rename ace_time::provider to ace_time::clock and rename
    SystemTimeProvider to SystemClock.
  • Add HelloSystemClock example code.
  • Add isValidYear() into various forComponents() methods to check
    int8_t range of year component.
  • Rename DateStrings::weekDay*() methods to dayOfWeek*() for
    consistency.
  • Change ZonedDateTime::printTo() format to match Java Time format.
  • Remove friend declarations not related to unit tests.
  • Remove redundant definitions of kInvalidEpochSeconds, standardize on
    LocalDate::kInvalidEpochSeconds.
  • Make timeOffset a required parameter for constructors and factory
    methods OffsetDateTime instead of defaulting to TimeOffset().
  • Make timeZone a required parameter in constructors and factory methods
    of ZonedDateTime.
  • Fix BasicZoneSpecifier::getOffsetDateTime() to handle gaps and overlaps
    in a reasonable way, and perform some amount of normalization.

0.1 - initial release

• 0.1 (2019-06-15)
  • Initial release on GitHub to establish a reference point.