BUG: Disable AutoRestart to workaround issue #2535

Instead of asking the user if he would like to restart, he is asked
if he would like to exit Slicer and manually restart.

The restart confirm dialog is associated with the
settings key "MainWindow/DontConfirmExit"

See #2535

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22400 3bd1e089-480b-0410-8dfb-8563597acbee