Fixed the Plot parser piggy backing off the QuestParser
Added a parse(String json) method and corresponding static parse(String json, Class clazz) method to SuperParser, so that a String can be parsed entirely as one object instead of requiring member references
Removed MapSet because it removed all purpose from World
Added a GameMap superclass for Building and Grid.  It has a name, and abstract methods getEntities() and getGrid(int index)
The World now holds a map of GameMaps, and the worldGrid and buildings are not distinguished within the map except by name