Topic/refactor

To Do:

• finish refactor muscle geometry
• add kinematic constraint test
• test parsing
  • inertia parsing
  • pose of joints parsing
• add kinematics test
• add dynamics test
• add inverse dynamics algo + test
  • Find a way to compare aba/forward_dynamics ?
• tests for actuators
• markers from opensim
  • Sensor frames for now
• Redo the init files better
• write a bit of doc ...
• Put the geometry model somewhere for visualization
• Fix conditional and moving point init
• Add universal joint to opensim parser