[ODE] new stuff: ray geom class, point depth functions, tests

[Russ Smith]

i have added a ray geometry class to ODE. read the new 'ray' section in
the docs - the behavior is slightly different from erwin's ray class. in
particular, the ray contact normals are the surface normals, not the
reflection axes. if you want a reflection axis (e.g. for projectile
bounce or ray tracing) it can be easily derived from the ray
direction and the surface normal (i should provide a function to do this
i guess...).

i've also added a buch of dGeomXXXPointDepth() functions, which help a
lot in collision testing and may have some other uses. speaking of
which, i've created a new collision test infrastructure in
test_collision.cpp, and i've added a bunch of tests for the stuff i've
just added. more tests will come with time.

russ.

-- 
Russell Smith
http://www.q12.org