TAI initialization, improved i18n, improved sourcemaps, etc. (#16)

* Added option to initialize `DateTime` object with TAI.
* Made timezone names case insensitive.
* Added `DateTimeFormatOptions` options to Ixx format strings.
* Improved i18n support for AM/PM time formats.
* `newDateTimeFormat` function for creating DateTimeFormat instances with more flexible options.
* TAI treated as named timezone or displayed with formatted UTC offsets.

Author: kshetline

.npmignore

@@ -7,6 +7,7 @@
 /docs
 /img
 /.nyc_output
+/.vscode
 *.js.map
 !/dist/**/*.js.map
 *.spec.d.ts
@@ -17,3 +18,6 @@
 /test.html
 .travis.yml
 .coveralls.yml
+.markdownlint.json
+.nycrc
+rollup.config.js

README.md

@@ -149,6 +149,7 @@ While there are a wide range of functions and classes available from **@tubular/
 | `ttime('2017‑03‑02 14:45 Europe/Paris')` | From an ISO-8601 date/time (variant with space instead of `T`) and IANA timezone. | `DateTime<2017-03-02T14:45:00.000 +01:00>` |
 | `ttime('20:17:15')` | Dateless time from an ISO-8601 time string. | `DateTime<20:17:15.000>` |
 | `ttime(1200848400000)` | From a millisecond timestamp. | `DateTime<2008-01-20T12:00:00.000 -05:00>` |
+| `ttime({ tai: 1200848400000 })` | From a TAI millisecond timestamp. | `DateTime<2008-01-20T12:00:00.000 -05:00>` |
 | `ttime({ y: 2008, m: 1, d: 20, hrs: 12, min: 0 })` | From a `DateAndTime` object, short-style field names. | `DateTime<2008-01-20T12:00:00.000 -05:00>` |
 | `ttime({ year: 2008, month: 1, day: 20, hour: 12, minute: 0 })` | From a `DateAndTime` object, long-style field names. | `DateTime<2008-01-20T12:00:00.000 -05:00>` |
 | `ttime([2013, 12, 11, 10, 9, 8, 765])` | From a numeric array: year, month, day, (hour (0-23), minute, second, millisecond), in that order. | `DateTime<2013-12-11T10:09:08.765 -05:00>` |
@@ -247,7 +248,7 @@ Please note that, as most unaccented Latin letters are interpreted as special fo
 | | SSSS... | Additional zeros after milliseconds. |
 | Timezone | ZZZ | America/New_York, Europe/Paris, etc.<br><br>IANA timezone, if available. |
 | | zzz | Australian Central Standard Time, Pacific Daylight Time, etc.<br><br>_Long form names are only for output &mdash; cannot be parsed._ |
-| | ZZ | -0700 -0600 ... +0600 +0700
+| | ZZ | -0700 -0600 ... +0600 +0700<br><br>If used with a TAI time, the displayed offset will be the difference between TAI and UTC at a given moment in time. Outside of the well-defined span of officially-declared leap seconds, this offset might be displayed with millisecond precision.
 | | zz,&nbsp;z | EST, CDT, MST, PDT, AEST, etc.<br><br>Please note that timezones in this format are not internationalized, and are not unambiguous when parsed. |
 | | Z | -07:00 -06:00 ... +06:00 +07:00
 | Unix timestamp, UTC | X | 1360013296 |
@@ -295,6 +296,12 @@ The capital letters `F`, `L`, `M`, and `S` correspond to the option values `'ful
 | IS | `9/4/86` |
 | IxL | `8:30:00 PM EDT` |
 
+You can also augment these formats with brace-enclosed `Intl.DateTimeFormatOptions`, such as:
+
+`IMM{hourCycle:23h}`
+
+...which will start with whatever the localized time formatting is and force it into 24-hour time, whether the standard localized form is a 12- or 24-hour format. Note that no quotes are placed around the option values, as they would be in JavaScript/TypeScript code.
+
 ## Pre-defined formats
 
 ```javascript
@@ -1598,6 +1605,18 @@ For a given UT1 Julian Date (Universal Time), return the Julian Date in ephemeri
 ttime.utToTdt(timeJDU: number): number;
 ```
 
+Create new `Intl.DateTimeFormat` instances with more flexibility for mixing options. For instance:
+
+> `new DateTimeFormat('ja', { timeStyle: 'short' })`
+
+... shows hours with no leading zero for single-digit hours. If you try to add the leading zero like this:
+
+> `new DateTimeFormat('ja', { timeStyle: 'short', hour: '2-digit' })`
+
+...an exception is thrown. By using `newDateTimeFormat`, however, `@tubular/time` will attempt to override `dateStyle` and `timeStyle` options with specific variations which are otherwise disallowed.
+
+`ttime.newDateTimeFormat(locales?: string | string[], options?: DateTimeFormatOptions)`
+
 ## Constants available on `ttime`
 
 ```typescript