Jeck - [JGE recompile needed] Shop cleanup, Interface enhancements.

Added basic transition system that works with GameApp's phases. Currently does a fade-out between elements, which works well in some places and not-so-well in others. We'll definitely want to think about where and where not to use it... they'd work a lot better if we could spawn a thread to handle loading the next state while transitioning.

Also cleaned up the shop a bit, so it uses ReadButton() instead of GetButtonClick()-- hence the slight change to JGE. Added a tiled image for the task board, which loads conservatively (I tried 128x128, but it didn't look as good).

JGE/include/JGui.h

@@ -94,6 +94,7 @@ class JGuiController
 
   virtual void Render();
   virtual void Update(float dt);
+  virtual bool CheckUserInput(u32 key);
 
   void Add(JGuiObject* ctrl);
   void RemoveAt(int i);