Add sample-timer for calls
Style fix
Fix units (us -> ms)

Got off a factor of a thousand, this would've never worked.
Now it should handle the calls properly.
Fix timing issue

I don't know why I missed that

1) of course we have to check tv_sec, not tv_nsec
2) when we do a nanosleep, but use the "now"-val for the lastsent-
   time, we obviously keep the wrong time.
   This leads to the program thinking more time elapsed than really
   has, leading to less nanosleep and thus higher playback-speed.

Now this is fixed, and apart from state-transition issues,
call-receiving now works perfectly. ;)
Properly hang up initiating calls
Clean up calls on shutdown
Allow simultaneous tx/rx call
Factor out check for NULL frame
Allow to attach aplay after we've initiated a call
Re-order function decls
Reset state after hangup
Nuke leading space
Reset fd offset when writing out