Offsets in custom sprites, and other improvements

- make left/top in input file optional (default is 0)
- make width/height in input file optional (default is remaining width/height of the image)
- add x/y offsets to new sprites for proper positioning
- fix generated parser to allow compiling at windows
- make uint8 and uint32 generally available
- add automagic cropping of the image
- increase version number of custom sprite file to prevent confusion with older files