Release v2.0.0

Changes since v1.1.2:

• ⚠️ breaks backward compatibility ⚠️
• trajectories are represented by objects from the Curves package and
  not with discrete set of point
• additions and changes to several fields to the contact-phase structure
  to store data about the whole body motion
• Contact-phase now contains the active contact patchs in a map
  <effector name ; contact patch >