Waypoints update

A few changes here: (@bit-pirate update this if I miss anything)

* Move several functions from headers -> cpp files
* Reverse characteristics for the safety controller
* Args enabled cmd_vel_mux launcher
* Args enabled velocity smoother launcher

The significant changes for review:

* Overhaul of waypoint manager (manager + yocs_waypoint_navi -> provider + yocs_waypoint_navi)

I guess this probably should wait until after roboworld, but start discussion on merging gopher and waiterbot implementations here.