Image collision detection

[John Craig]

For anyone interested in image collisions, I have uploaded a demo to 
user space Jock_McTartan.  I'll upload a library file shortly for using 
in your own projects.  Feedback would be appreciated - IMHO it's pretty 
fast even with reasonably large images.  Intended for use with PNG 
images, it has pixel level collisions and a transparency threshold 
setting to avoid collisions with object shadows, etc.

JC