Fix typos + Starting Eigen port.

...TrajectoryGeneration/FootTrajectoryGenerationStandard.cpp

src/MotionGeneration/ComAndFootRealization.hh

src/PreviewControl/PreviewControl.cpp

src/ZMPRefTrajectoryGeneration/OrientationsPreview.cpp

src/ZMPRefTrajectoryGeneration/ZMPVelocityReferencedSQP.cpp

src/ZMPRefTrajectoryGeneration/qp-problem.cpp