Merged HandC into manipulatorDynamics, did some cleanup in manipulatorDynamics.
External force gradients in manipulatorDynamics. Fixed bug in getSubMatrixGradient.
Moved f_ext_map_from and f_ext_map_to from RigidBodyManipulator.featherstone to RigidBodyManipulator, got rid of RigidBodyManipulator.featherstone.
interleaveRows bug fix (for now).