add ability to identify a parallel text for display in a reading container

[balmas]

building off of #116 , I'd like it to be possible to both automatically identify and select a parallel translation of a text and offer the user the ability to select from a list. Then we could use the new translation display to display the source text and translated text side by side.

[PonteIneptique]

I think though it should be an extension, not a mandatory route :)