New commentary type field on witness fragment

[cubap]

For gloss-transcription.html and gloss-witness.html, we need to add a field to encode the type of commentary along with the gloss we are attaching. Both interfaces need the same encoding.

[cubap]

Probably labeled "Gloss format" and encoded as "_glossFormat" unless there are disagreements.

[cubap]

A dropdown element with enum [ "marginal", "interlinear", "appendix", "other" ] with none selected as a possible option.

[thehabes]

Generally handled by "Notes" right now. However, we imagine more public facing discussion and other commentary which would need to be captured by a distinct input field. This would overload the capabilities of the "Notes" field, which is meant to be internal.