Addresses suggestions made during this PR.
1. Component methods and comments better organized into groups
2. RollingOnSurfaceConstraint case in testConstraints no longer uses stack allocations.
3. Transform axis comments updated to reflect that axis function is NOT optional just has a reasonable  default.
4. testComponents uses SimTK::Array so that ownership is not assumed (which ArrayPtrs takes by default)
5. testModelCopy test copy constructor and clone.