Merge branch 'topic/cmomentum' into 'devel'

bindings/python/crocoddyl/crocoddyl.cpp

bindings/python/crocoddyl/multibody.hpp

.../python/crocoddyl/multibody/costs/centroidal-momentum.hpp

include/crocoddyl/multibody/costs/centroidal-momentum.hpp

src/CMakeLists.txt

src/multibody/actions/contact-fwddyn.cpp

src/multibody/costs/centroidal-momentum.cpp

unittest/test_costs.py

unittest/testutils.py