(trunk, gtk) #5450: in transmission-gtk's main.c::on_app_exit(), check to see if shutdown's already been initiated so that we don't call tr_sessionClose() twice.

git-svn-id: svn://svn.transmissionbt.com/Transmission/trunk@14154 f4695dd4-2c0a-0410-b89c-da849a56a58e
(trunk, libT) #5451: 'crash in tr_torrentGetPeerId() during incoming encrypted handshake' -- fixed.

git-svn-id: svn://svn.transmissionbt.com/Transmission/trunk@14155 f4695dd4-2c0a-0410-b89c-da849a56a58e
(trunk, libT) #5452 'preventing zombies from child scripts' -- fixed.

git-svn-id: svn://svn.transmissionbt.com/Transmission/trunk@14156 f4695dd4-2c0a-0410-b89c-da849a56a58e