Hand resolution of some conflicts

Remove first column of gait matrix that contained the duration of each gait phase. Now gait matrix has one line for each timestep.

New organization and bidings to call Gait, FootstepPlanner and FootTrajectoryGenerator directly from Python

* Code cleaning and refactor
* Add Types, FootTrajectoryGenerator, Gait, FootstepPlanner classes
* Rename quadruped-reactive-walking qrw

Authored-by: Fanny Risbourg <frisbourg@laas.fr>

Reswitch to old estimator values + Put back things that should not have been cleaned + Try fixing gepetto viewer

Add contact force limitation when a contact is activated to avoid directly applying a huge force (ramp shape for the limit)