Skip action_queue_on_change_position if patient not in queue

When a patient left the queue to be treated in a room while using the
drinks machine, after using the drinks machine the on_change_position
callback would be executed. That callback would enqueue actions to use
the bench again, like the user was still queued. The patient would
then use the bench forever.
Fix tryToFindNearbyPatients for patients using the drinks machine

When a patient in a queue is found and removed from the queue by
tryToFindNearbyPatients, the 'queue' actions is_in_queue flag
must be set to false. Otherwise, when the patient is using the
drinks machine at the moment of the rewrite, the after_use callback
of the drinks machine would create a new walk/use_bench or idle action
for the old queue.
Workaround for patients that fell of a queue

The workaround for patients, that fell of a queue, checks for patients
sitting on a bench while being queued, but are not found for 2 ticks
in the queue. It could happen sometimes, that in the moment before the
tick the patient was dequeued and doing the standing-up anim, which
requires the tick counter. When the patients problem is verfied he
is being sent to the reception.
Merge pull request #377 from phillipp/patient-queue-fix

Patient queue fixes plus savegame workaround