Lock screen during call about csipsimple HOT 2 CLOSED

Done in -12-25 (was done since a while but at least -12-25 is ok with this 
feature).
Both proximity sensor and timer are ok.
Important notice :
* As for some device (particularly nexus one), turning off screen implies wifi 
to enter PSP mode, there is an option in settings to keep screen enlighten 
while in call (UI settings).  
* For other devices, provided the fact settings is well set to not keep awake 
while in call,as there is no public api to turn off screen, there is a screen 
locker overlay and screen will turn off when the android timer has expired 
(depends on user settings).