GUI Wrapper VI - The Implementation, Part III

-Credits and GameOver UI's now use the GUIManager
-Improved coding of High Score Initials

Other fixes:
-Player.cs: Changed code to allow perceptual and Keyboard input
-Gun.cs: Created number checking to make sure the number is from 0-9.
-MasterController.cs:  Removed Selector<Texture>, redundant.
-CreditsUI.cs: Removed the derp debug