[end effector] add waypoint definition for curve with 3 free var

include/bezier-com-traj/definitions.hh

include/bezier-com-traj/solve_end_effector.hh

include/bezier-com-traj/utils.hh

...traj/waypoints/waypoints_c0_dc0_ddc0_j0_j1_ddc1_dc1_c1.hh

...j/waypoints/waypoints_c0_dc0_ddc0_j0_x3_j1_ddc1_dc1_c1.hh

include/bezier-com-traj/waypoints/waypoints_definition.hh

src/computeCOMTraj.cpp

src/solve_0_step.cpp

src/utils.cpp

src/waypoints_definition.cpp