Breaking changes in C interface

• remove ocp_nlp_solver_opts_update, opts_update is called in ocp_nlp_solver_create
• cleanup of redundant signatures:
  • signature of ocp_nlp_get_from_iterate changes (takes solver and not solver AND dims)
  • signature of ocp_nlp_set changes (takes solver and not solver AND config)
  • signature of ocp_nlp_get changes (takes solver and not solver AND config)
  • signature of ocp_nlp_get_at_stage changes (takes solver and not solver AND dims AND config)
• setters for lb and ub have been removed

Other

• formatting wind_turbine C examples, chain example