Fix possible stack corruption when parsing friend IDs
Send the actual message when initiating the friend request
Revert accidental modification to config.mk
Allocate enough memory to allow copying all the friends
Add support for changing the user state and reporting friend's user state
Correctly inform external scripts of an invalid user state
Rename ustatus to ustate
Refactor user-state-logic
Simplify user state tracking
Remove debug printf()
Release call resources with toxav_kill_transmission()

Reject calls on both sides to reset states.  This still needs
to be tested to see if there's any effect of doing that.
Update TODO
Increase ringing delay
Implement peer timeout
A bit more consistent output message