Merge pull request #40 from fvalenza/topic/CRTP

benchmark/timings.cpp

src/multibody/constraint.hpp

src/multibody/joint/joint-base.hpp

src/multibody/joint/joint-free-flyer.hpp

src/multibody/joint/joint-planar.hpp

src/multibody/joint/joint-prismatic.hpp

src/multibody/joint/joint-revolute-unaligned.hpp

src/multibody/joint/joint-revolute.hpp

src/multibody/joint/joint-spherical-ZYX.hpp

src/multibody/joint/joint-spherical.hpp

src/multibody/joint/joint-translation.hpp

src/spatial/force.hpp

src/spatial/fwd.hpp

src/spatial/inertia.hpp

src/spatial/motion.hpp

src/spatial/se3.hpp