Filled in missing calcContactPatch() functionality for HertzCircular & Elliptical contact details.

Simbody compliant contact normally calculates only the resultant force and other info needed to advance the simulation. On request, you can also get detailed "patch" information (sometimes called the "contact manifold"), consisting of both the resultant and one or more contact "elements", like triangles in an elastic foundation mesh.

For Hertz contact there is only a single detail element, but that wasn't being filled in. Some of that info is useful, particularly the sliding velocity. I copied over the code from the new brick contact element which did fill in that info, so now you can ask for the contact patch for Hertz contacts and display the result.

Peak pressure and patch area are still not being filled in.