Fix for 'Crash double-clicking any knob in debug build (git master) (#948)'

Conflicts:
	src/gui/widgets/knob.cpp
Merge branch 'stable-1.1' into fix_for_doubleclick_knob_bug
Make syntax for fix more consistent with existing code.
Made isEmpty function name more specific. Moved doubleclick fix to restoreJournallingState.
Fix syntax a bit.
Change isJournallingStackEmpty to isJournallingStateStackEmpty
Merge pull request #1145 from krafczyk/fix_for_doubleclick_knob_bug

Fix for doubleclick knob bug