UpdateIII 12 June 2014

Added sprite manager class to load sprites from image files. It starts
by checking if it has a sprite of the specified name stored, and if so
uses it. Otherwise it will make a new sprite and search for a texture of
the same name to apply to the sprite. If no such texture is stored, it
will load said texture from an image file of the same name in the
directory specified in the Initialize method for the class.