[OE-3214] bugfix for crash when saving sessions
[OE-3124] theatre diary fix worked on with jamie
fixed Housekeeping script
Merge branch 'master' of github.com:openeyes/OphTrOperationbooking
added comment
fixed second occurrence of same bug
Merge branch 'master' into release/1.4

Conflicts:
	commands/HousekeepingCommand.php
	controllers/TheatreDiaryController.php
	models/Element_OphTrOperationbooking_Operation.php