Some added constraints for review children and images plus dialog listener callbacks for adding and editing.

Added InputHandlerChildren to check if child subject not already present. Ditto for bitmaps in GVImageList.

Dialog callbacks added to allow boolean 2-way communication between dialogs and commissioning fragments for success flags. Before dialogs could message fragments but not vice versa so dialogs would update e.g. titles on Add press regardless of whether data was added successfully. Makes things a touch more messy and separated compared to the previous OnActivityResult() messaging which worked for both dialogs and commissioned activites e.g. for Locations/URLs. Now OnActivityResult is for Location/URLs and everything else uses dialog listeners. A bit messy.