tern: convert our custom markdown to dfxp during the migration
Merge remote-tracking branch 'origin/dev' into dev
tern: writelock languages during version sync too
tern: escape XML in subtitles

In the future we may or may not want to move this into the pipeline.  But for
now let's just do it here.
tern: fix translation source lookup
1917: Restored the translation source language  display on the subtitle view
Merge branch 'dev' of github.com:pculture/unisubs into dev
Merge branch 'dev' of github.com:pculture/unisubs into dev