Adding support for model listeners and adding missing tests.
Added a test for the korma combobox model and updated the listener list to use a list instead of a set.
Added a test for the list renderer file.
Deprecated a fuction already supported in seesaw.
Added a test for the table renderer file.
Implemented the create and delete group buttons.
Implemented the edit group button.
Switched the model listeners to model interceptors and fixed a bunch of failing tests.