Sign types are not in the coding schema file

[gregorydimitriadis]

Sign types (lexical, fingerspelled, etc...) are not currently in the coding schema file. To my knowledge they never have been, but it's maybe a thing we should add. Would require a bit of refactoring.

[cneidle]

Sign types (for loan signs, number signs) are currently properly inserted from the Sign Bank when we 'insert all data'. Number of hands, marked number of hands, passive base arm are also properly inserted.