Got a good chunk done, but you'll want to review this before merging.

I wasn't sure how to succinctly summarize the difference between some of the similar functions. So you might want to double check the notes in the body of the definitions in `manual.scrbl` for: 

* `tox_get_self_name_size`
* `tox_get_self_status_message_size`
* `tox_get_self_status_message`
* `tox_get_self_user_status`

I just gave `tox_set_status_message` and `tox_set_user_status` the same comments.