(svn r11174) -Codechange: add possibility to show the bounding boxes of sprites using CTRL-B so one can get a better understanding of the used bounding boxes to fix the glitches that still exist. Patch by frosch.
Note that this is not completely glitch free, bounding boxes sometimes aren't removed properly. This is due to the fact that the bounding boxes sometimes are larger than the sprite, which causes a smaller part than the bounding box to be redrawn. This is NOT a bug, but a known implementation limit as we do not want to slow down normal games so the debug graphics are always 100% correct.