Merge pull request #147 from indivisibleatom/CS4496

Cs4496
Merge pull request #148 from indivisibleatom/CS4496

Scaling  urdf, linear collision between static and moving shapes.
merged
merged
moved collision handling; create momentum data members
added linear momentum
set nonzero restitution coefficient
added fluid app
undef for IX before redef, add to CMakeLists