* Fix duplicated language entries from system and app language sets.
Closes#2900
* Prefer modern language codes.
Closes#2903
* Synchronize per-account default posting language with server.
Closes#2902
* Allow users to post in languages android doesn't know about yet (e.g. toki pona)
* Always put the preselected language at the top of the list
* Add UI for selecting post language
* Apply selected language when sending status
* Save/restore post language with drafts
* Fall back to english if the configured language isn't found in the locale list (no-NB)
* Remove comment about no_NB
* Move language dropdown to top of compose view
* Preserve language when redrafting
* Set default language to target post's language when replying
* Add Tusky license header to new source file
* Tweak language dropdown button width