2.0.0 / 14.01.2018

Moved RelativeTimeFormat to a separate relative-time-format package.
(breaking change) Removed .locale() static function. Use .addLocale() instead.
(breaking change) flavour property renamed in non-single-word cases: underscores (_) got replaced with dashes (-). Examples: short_convenient -> short-convenient, long_convenient -> long-convenient, short_time -> short-time, long_time -> long-time. The relevant keys in locale index.js files got renamed the same way.
(breaking change) RelativeTimeFormat is no longer exported from this library.
(could be a breaking change) Re-did /prop-types, /gradation, /cache exports as sub-packages. This could possibly change their import behavior. Maybe /prop-types did change — I changed some export strategies for it.
(unlikely a breaking change) yue-Hant locale removed (due to its removal from CLDR).
(unlikely to be a breaking change) Removed handling for a case when "now" unit had "past"/"future" which is an object of quantifier messages instead of a string. The rationale that having "now" unit with "past"/"future" which are objects of quantifier messages wouldn't make sense because "now" is a moment and one can't differentiate between "past moment", "current moment" and "next moment" in real life.

1.0.33 / 29.11.2018

Resolved cyclic dependency between JavascriptTimeAgo.js and RelativeTimeFormat.js.
JavascriptTimeAgo.default_locale variable no longer exists (it wasn't public or documented).

Added .addLocale() alias for .locale() function (better naming). The old .locale() function name is now deprecated and will be removed in some next major version release.
Added RelativeTimeFormat.addLocale() proxy function which simply calls JavascriptTimeAgo.addLocale().

Refactored twitter style and styles overall: style can now have threshold(now) function and also gradation step can have format(value, locale) function instead of unit.

Renamed fuzzy style to time.
Refactored gradations and styles.
gradation is now not being exported from index.js along with day, month and year (one can still import it manually from gradation.js).
es6 folder got renamed to modules
build folder got renamed to commonjs

Renamed plural to quantify inside locale data.
Implemented Intl.RelativeTimeFormat proposal polyfill which is now being exported.

(can be a breaking change for custom styles) Renamed just-now unit to now and xxx-concise flavour to xxx_time (+ flavour .json files got renamed accordingly).

(breaking change) When defining a custom style its override() function takes date and time parameters: now date parameter of override() is not guaranteed to be set (can be inferred from time).

(breaking change) Due to a long-standing engineering flaw in intl-messageformat library (the locale data loading process) I dismissed it and this library is now using raw CLDR locale data instead so built-in locale data now holds an extra property: the plural function taking a number and returning the pluralization type of that number ("one", "few", etc). Therefore, if adding raw CLDR locale data for locales which are not built-in this pluralization function must be passed as the second argument to .locale(localeDataCLDR, pluralsClassifier).
(breaking change) javascriptTimeAgo.styles is no more accesible: pass style as a string instead.
(breaking change) locales folder inside the package renamed to locale (e.g. javascript-time-ago/locales/en -> javascript-time-ago/locale/en).
style.flavour can now be an array