Improve movement switching between calls.
Improve movement switching between calls.

Supports case when user hangs up a call while an incoming call is in place.
Bug Fix: No longer switches caller's name when pausing a current call when there is another pause call.
Also some refactoring for calls manager.

wilfreddekok/Antidote,dvor/Antidote,dvor/Antidote,Antidote-for-Tox/Antidote,Antidote-for-Tox/Antidote,wilfreddekok/Antidote,wilfreddekok/Antidote,Antidote-for-Tox/Antidote,dvor/Antidote,wilfreddekok/Antidote,dvor/Antidote,Antidote-for-Tox/Antidote