Migration from version `1.x`

`.locale()` function removed.

If there're any .locale() static function calls then replace them with .addLocale().

`flavour`s that got renamed.

If any custom styles were defined replace the following flavours in their definition:

short_convenient -> short-convenient
long_convenient -> long-convenient
short_time -> short-time
long_time -> long-time

`RelativeTimeFormat` is no longer exported

If RelativeTimeFormat was imported from javascript-time-ago then it must now be imported from relative-time-format instead.