Versions and releases

[VipSaran]

It would be very useful to have some kind of versioning for l10n.js, both on the github page via releases (which are simply created by tagging a commit) and within the file itself. Otherwise (as it is now), it is hard (read: impossible) to track newer vs. older versions, especially in regard to fixed bugs.

Additionally, it would be useful to have the version changelog documented for each release, but this is not so essential.