Remove collisionmex.cpp
Uncomment IK infrastructure from CMakeLists.txt

Builds successfully.
Fix closest-distance section of update ptr mex.
Fix valve_task_wall.urdf collision elements.

The origin tags on the collision elements didn't match those of the visual
elements. Also, the entire file was a single line.
Add 'use_contact_shapes' flag to BotVisualizer.

If `options.use_contact_shapes` is true the visualizer draws the contact
geometry *instead of* the visual geometry.
Fix AllBodiesClosestDistanceConstraint

testKinCnst now passes with the AllBodiesClosestDistanceConstraint section
uncommented.
Remove the Atlas model model_simple_visuals.urdf

This has been replaced by atlas_chull.urdf. One collision element per body is
more efficient for collisionDetect.
Only check 10 poses in collisionDetectGradTest.
Change warning in RigidBodyCylinder/getPoints

Original warning was misleading, as the 3D collision detection is *not*
treating the cylinder as box. We do want a warning here though, lest users
think that they're getting some mesh approximation to the cylinder.