fix comments of some files
Merge pull request #60 from nurupo/master

Don't assume that all callbacks are set.
Merge branch 'master' of https://github.com/sometwo/ProjectTox-Core into sometwo-master

Conflicts:
	core/Messenger.c
Fixed comments in other files as per request of jvrv
More changes made to comments, as requested by jvrv
Merge pull request #62 from Captainhat/master

More comments in core fixed