added example with pinocchio and casadi

[examples | add] quadrotor with control bounds

[ms-nlp | modif] added control bounds

[ms_nlp | modif] using data structure to store temporary variables

[ms_nlp | modif] using data structure to store temporary variables

[examples | feature] added quadrotor and double pendulum

[ms-nlp | modif] bug-fix with indeces. quadrotor working

[ms_nlp | wip] quaternion implemented but with errors

[solver | modif] added warm start option and max iter

[examples | feature] added example with talos arm

[examples | feature] added example folder

[bindings | feature] added python bindings for SolverIpOpt

[solver-ipopt | feature] Added solver Ipopt

[multiple-shooting | feature] Added library to user croco problems with non quaternion state

[example] simple example to test IpOpt interface