SetBit(kcanDelete) is removed and the signal Closed() of the canvas is connected
to the slot TurnOff of TTimer. These changes avoid the SegV when closing the
canvas application and using .q command in root.


git-svn-id: http://root.cern.ch/svn/root/trunk@12447 27541ba8-7e3a-0410-8455-c3a389f83636