support literal glosses for words

[Daniel W. Hieber]

\ltg: literal gloss
\ltw: literal word
\w: word - This is being used for the word transcription
\wg: word gloss
\wl: word literal
\wlt: word literal
\wt: word translation | word transcription

These should either not contain white space, or should be surrounded by brackets. Otherwise parsers cannot align the literal glosses to their words accurately. (This is an instance where the scription format is more rigid than the DLx JSON format. The JSON format would allow for spaces in a literal gloss.)

May be in multiple languages. Must have valid ISO language tags.