New patches: 2 new joints and some optmization

Hi,

I submitted some new patches on the SourceForge web site.


The new patches includes small optimization and code cleaning.

But the important part of the patches are 2 new joints.

The first joint is a Piston. It is a joint similar to the slider but the 
2 bodies are free to rotate around the sliding axis.

The second joint is a joint combining a prismatic and 2 rotoides joints.
(or in ODE terms a slider and a universal joint).

I was talking earlier on the list about the 2 new joints and people were 
requesting the code so I created the patches.

So people who use the patch can you send feedback to the list about the 
joint this will help clean the code and include the joints into the code 
base of ODE.

(N.B. I'm using the joint in a simulator for the last 3 months so the 
code should work well.)

Remi