please add some documentation

[rlisper]

Hello, I was interested in your work but many things I do not uderstand. At first I tried to build your's demo files but it does not working - some use functions does not match to now defenitions. I rewrite this controversial things but I havent enough info to do it correctly. Can you report for users some common things as:

• what is body and shape and how to built correctly a physical object?
• what rules everyone should use to build a world?

I'm a little experimenting with your code and now have like this:
http://paste.lisp.org/display/131299

thanks in advance