Remove the 'Hook' and 'Cardano' joints with the link-lock formulation.

The 'Hook' joint was effectively a duplicate of 'Universal' (using 2 different rotational DOFs).
Add new joint ChLinkUniversal, with the kinematics commonly associated with a 'universal' joint.

TODO: implement calculation of reaction forces/torques.

Note that the link-lock formulation does not allow proper modeling of a universal joint (in the sense of the definition commonly used, at least in the US).  The resulting 2 rotational degrees of freedom joint with the link-lock formulation (the current ChLinkLockUniversal) may actually be a constant-velocity joint.  I need to check this;  if this is indeed the case, we will rename this joint to something like 'ChLinkLockConstantVelocity'; otherwise, we will simply remove it.
Merge branch 'feature/univ_joint' into develop
Merge branch 'develop' of https://github.com/projectchrono/chrono into develop