Cleaned up MapLoader a little
Moved get/setRoom up to Entity

Sinve most (if not all) Entites will be inside of a room at some point
it makes sense to move this up int the heirarchy. This allows
construction of objects lower in the hierarchy by supplying a nullptr as
the "room" which can be set (or not?) later.
Created ItemFactory (but it still needs work!)

This is a basic inferface for an ItemFactory but all of the construction
hard coded. I want to defer the construction to somewhere else but for
now this will do. Eventually this will work by cloning prototypes but
for now hard-coding gets us rolling.
Testing the ItemFactory in MapTestState

Replaced the Item creation by calling the factory method. It works!