cleanup
now showing previously missing gui elements

just moved them in front of the gui background
removed more Slick code

SlickExceptions and GameContainers
removed anoter SlickException
better x Coordinates for all Sprites
Sprites now have correct y position, too
cleanup
readded tower shadow
LibGDXRectangles now rendered at correct positions

they use the same code as the Sprites for the correct y Position
cleanup
reimplemented color and alpha for OwnSprite
buttons are unpressed after each tower placement