This allows duplicate items to appear in a collection and still be selected independently. Previously, all collection view selection was done per object, which would mean the first instance of the object in the content was always selected. Instead, selection is done by index only so that the same object can appear many times and each be selected separately.
Restricts selection by index to being enabled so that selection by object still works when necessary.
Removes commented out code.
Fixes failing local unit tests (invalid layouts provided).