[ODE] xml model reading and writing plus trimesh mass properties calculation

[Evan Drumwright]

Hi All,

I have written an extension to ode, with an API highly similar to that of 
ode, that supports reading and writing of dynamics models using XML.  For 
those of you familiar with the Vortex simulator, the format used by odeXML 
is very similar.  Additionally, this library has the capability to read and 
write the state of the simulator.  Finally, I have included a utility to 
calculate mass properties (mass, center of mass, and inertia tensor) of 
triangle meshes.

Some parts of the library have not been fully tested (see my web page on 
odeXML for more details), but will be soon, as I'm using this library for my 
Ph. D. thesis.  Other parts have been tested, and work great.  So, with that 
caveat in mind, I'm going ahead and making this available for download.

I've provided Makefiles and tested odeXML on linux and OS X.  Sorry Windows 
users, you're on your own for now.

More information and download available at:

http://robotics.usc.edu/~drumwrig/code.html