The getActivityByUUID now gets the real activity, rather than the hibernate CGLIB version, to avoid classcast errors when updating an activity in authoring.
Fixed bug - tool content id was not being updated when a tool activity was updated. The code that handles the special fields for tool activities, optional activities, etc wasn't being called.
The rule to work out whether to pre-initialise the tool session was wrong. Was initialising for grouped activities, we want to initialise the non-grouped activities.