Introduce a new PG dealing with the automatic foot step with non linear constraints.

include/jrl/walkgen/pgtypes.hh

src/CMakeLists.txt

src/Mathematics/relative-feet-inequalities.cpp

src/Mathematics/relative-feet-inequalities.hh

src/ZMPRefTrajectoryGeneration/ZMPVelocityReferencedQP.cpp

src/ZMPRefTrajectoryGeneration/nmpc_generator.cpp

src/privatepgtypes.cpp

tests/CMakeLists.txt

tests/TestHerdt2010DynamicFilter.cpp

tests/TestKajitaDynamicFilter.cpp

tests/TestMulticontactInverseGeometry.cpp

tests/TestNaveau2015.cpp