operator = and copy constructor for feet trajectories.

...TrajectoryGeneration/FootTrajectoryGenerationMultiple.cpp

...otTrajectoryGeneration/FootTrajectoryGenerationMultiple.h

...TrajectoryGeneration/FootTrajectoryGenerationStandard.cpp

...otTrajectoryGeneration/FootTrajectoryGenerationStandard.h

...neration/LeftAndRightFootTrajectoryGenerationMultiple.cpp

...Generation/LeftAndRightFootTrajectoryGenerationMultiple.h

src/Mathematics/PolynomeFoot.cpp

src/Mathematics/PolynomeFoot.h

src/ZMPRefTrajectoryGeneration/AnalyticalMorisawaCompact.cpp

src/ZMPRefTrajectoryGeneration/AnalyticalMorisawaCompact.h

tests/TestMorisawa2007.cpp