Reworked the Exit and Selection tools so that they now work with the refactored Model layer.
Rewrote the code so that it works with the newly polymorphic data layer.
Rewrote some code to work with the newly polymorphic model layer.
New images added.
Re-wrote code to work with the new polymorphic data layer.
Deletion of entities now factored out into its own class.
Rewritten to work with newly polymorphic data layer.