MPC-Walkgen: Comments on humanoid public API / Fix interpolation bug
              renaming "Ponderation", "DSPeriod", "DSSSPeriod", "nbStepSSDS"

Change-Id: I2d9b7c99e339787a348feede836184ab8183da1d
Reviewed-on: http://gerrit.aldebaran.lan:8080/18173
Reviewed-by: jjalcaraz <jjalcaraz@aldebaran-robotics.com>
Reviewed-by: agarcia <agarcia@aldebaran-robotics.com>
Reviewed-by: mdegourcuff <mdegourcuff@aldebaran-robotics.com>
Tested-by: mdegourcuff <mdegourcuff@aldebaran-robotics.com>
Reviewed-by: jlafaye <jlafaye@aldebaran-robotics.com>
MOTION: MPC-Walkgen - Fix test-humanoid

Change-Id: If5c6c581af46aa3f7be564d3750da5f311e203e2
Reviewed-on: http://gerrit.aldebaran.lan:8080/18267
Reviewed-by: agarcia <agarcia@aldebaran-robotics.com>
Reviewed-by: jlafaye <jlafaye@aldebaran-robotics.com>
Reviewed-by: mdegourcuff <mdegourcuff@aldebaran-robotics.com>
Tested-by: mdegourcuff <mdegourcuff@aldebaran-robotics.com>