stuff to do:

- add a smart mode detection routine that first tries fullscreen then windowed output
- add nearest mode matching, ie. ask for 512x384, it will center the display in the
  nearest graphics mode that is available, ie. it will fallback to 640x480 if required.
- something that would be really cool, ALT-ENTER switching between fullscreen and windowed(!)
- merge the vfw.c and the gdi.c into one target because they are so similar...?