Path rework

• Set up PathManager to handle path-related commands
• Set up register train command rg <train num> (initial version).
• Move pathfinding command from TrainAdmin -> PathManager.
• PathFinder writes to global path and looks for reverses. Has been tested
• PathPlanner is WIP, task to figure out timing and commands necessary when executing path. Uses code previously in ExecutePath. Rn is able of correctly working with reverses, finds sensors to stop on, saved switch commands. The existing capabilities work correctly. Note that there are cases where current code will not find all necessary commands due to the remaining TODOs. TODOs are documented in the file.
• Planned out work required for ExecutePath.
• Implemented ReservationManager, this is untested. TODO: reflect reservations on screen.

Merge other MR first