[Qt] FocusChanged changes

[Paul Ishenin]

Hello, Items specific to the Qt widget set

I removed SlotFocus of TQtWidget and added application FocusChanged hook 
to listen for all focus events in r14361. Also I removed piece of code 
on FocusOut event that Zeljan added few months ago (related with 
releaseMouse). Zeljan, please take a look - I hope that with new code we 
dont need that piece of code anymore.

Best regards,
Paul Ishenin.