Transcriptable behavior, autotranscription vendor

Moved out the romanization/transcription/transliteration stuff that was
in Sentence model.
Readapted transcriptions in the view.
Transcriptions for translations.
Using autotranscription for tools.
Config to disable transcriptions. Removed test returns.
Merge remote-tracking branch 'origin/master' into auto-transcriptions

Conflicts:
	app/models/sentence.php
Reintegrated gillux's fixes for romaji.
Renamed som stuff.
Updated comment.
Removed transcription const definition from Sentence model.
Merge pull request #445 from Tatoeba/auto-transcriptions

Moved transcription related code outside of Sentence model