Define some exceptions to raise if we try to delete something that's needed by Streampunk.
Raise them in the Room.delete() method.
Add test to make sure they get raised.
EnumTables should not allow us to delete the undef or default items, so add delete() methods to each subclass to stop that, and some tests.
No functional changes - just crossing the EnumTable tests off the list.
Tests for deleting rooms that have Room Capacity objects on them.