Added some methods to Shop to manage the prototype map
Added some methods to Shop to manage the prototype map

PinPinx/TD_Game_Engine,brandonnchoii/VOOGASalad,Jgilhuly/VoogaSalad,PinPinx/TD_Game_Engine,ninasun/game_engine,keikumata/CS308_Tower_Defense,keikumata/CS308_Tower_Defense,jeremydanielfox/game_engine,jeremydanielfox/game_engine,brandonnchoii/VOOGASalad,Jgilhuly/VoogaSalad,ninasun/game_engine