Fix crashes due to deleted Session pointers being kept around.
And fix LogoutJob never going through in the idle session, because the IdleJob runs forever. The idle job has to be stopped, first. Tested with kDebugs and using 'RMB / Toggle online/offline' Both fixes suggested by Kévin when discussing the issue with him. BUGS: 288268 CCBUG: 258271 FIXED-IN: 4.8