+ [OE-3436] fix cancellation date filtering
bugfix: site needed to be joined into the query
Merge branch 'release/1.4'
verify event isn't deleted
Merge branch 'release/1.4'
bugfix: some sessions don't have a firm (emergency list)
+ [OE-3461] if session is not available, it's not bookable
+ [OE-3461] give reason for unbookable when session not available
+ show site name in theatre booking
[OE-3461] fixed bug where sessions with cancelled bookings fail to display in the theatre diary
[OE-3464] fixed bug where if you print a letter from the event view it doesn't auto-confirm.
[OE-3462] fixed bug in the transport list where confirming an entry updates the booking last modified user/date.
Merge branch 'master' into develop