Not closing InVesalius when closing the project
Making possible to use Ctrl+q to close InVesalius
InVesalius was not exiting when closed via menu/close
Not using thread anymore to write session file
Only checking for update if invesalius/config.cfg has a id_random
It's not necessary to sys.exit in onclose
Updated the INVESALIUS_VERSION to beta4
Updated to beta4 in about dialog
FIX: Fixed ReadBlue stereo on Windows
Removed that annoying print "OnSize gradient"