Return an ImmutableMap now so people can't add/remove towns, nations, etc without calling the appropriate functions
Made all entities return ImmutableCollections now
Decided to use ImmutableList instead
Moved all the Maps out of the Datasource into MyTownUniverse so it will be easier to allow Datasource migrations later
Made MyTownUniverse a singleton. It is lazily loaded when doing MyTownUniverse.getInstance()
No idea what I have done :p