*Modified EFFECT_GOROUND so that it takes a center of rotation, angles work properly, and things don't move back.
*Updated the gui_gamecarousel files so that they are functional, shouldn't have any more code dumps, and use the EFFECT_GOROUND.
*The carousel button doesn't do anything anymore (since GOROUND was changed so much)
**Notes
*The easiest way test the carousel is to change guiGameGrid to guiGameCarousel in source/menu.cpp.
*If you compile with no modifications, the only noticeable difference is that the carousel button does nothing.
**Known Bugs in gui_gamecarousel
*The images dont line up horizontally (when shifting left they go too far left, and the same for shifting right). I think there is a rounding bug somewhere in GOROUND (I already fixed several).
*Cant hold down left and right to scroll yet
*Launching a game only works if the pointer is over two boxes
*If an image is growing when the carousel is turned, that button disapears
*If an image is grown when the carousel is turned, it wont shrink back
* remove the Disk-Shadow from dialogue_box_startgame.png (themers will scream). The Shadow now drawing from Loader
* little changes for Widescreen-prompt-fix
