talkatu/talkatu

Fill out some missing documentation to get our coverage back to 100%

Bring the docs up to 100% coverage.

Testing Done:
built the docs verified that `build/talkatu/reference/talkatu-undocumented.txt` has 100% coverage. Also ran the unit tests and demo to make sure nothing inadvertantly got busted.

Reviewed at https://reviews.imfreedom.org/r/91/
syntax: glob
*.pyc
*.ui~
\#*.ui\#
syntax: regexp
^artifacts\/
^build.*\/
^debian\/?
^packaging\/debian\/tmp\/
^packaging\/debian\/(.+\.)?(substvars|debhelper\.log)$
^packaging\/debian\/build.*\/
^packaging\/debian\/\.debhelper\/
^packaging\/debian\/debhelper-build-stamp
^packaging\/debian\/gir1.2-talkatu-0.0\/
^packaging\/debian\/libtalkatu0?(-.+)?\/
^packaging\/debian\/talkatu-demo\/
^packaging\/debian\/files$
^po\/.+\.pot$
^obj-.+\/
^old\/