Merge pull request #213 from jcarpent/topic/eigen3

CMakeLists.txt

src/multibody/constraint.hpp

src/multibody/joint/joint-prismatic-unaligned.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/spatial/inertia.hpp

unittest/constraint.cpp

unittest/tspatial.cpp