add tool to mirror trajectories (currently for ARMAR-6)
add a script to mirror motions, currently intended for ARMAR-6 joints (might directly work for ARMAR-DE and ARMAR-7, but not sure)
moved from https://git.h2t.iar.kit.edu/research-projects/eurobin/wp2-skills-nancy/-/tree/main/python/trajectory-tools/trajectory-tools?ref_type=heads based on a discussion with @gao