- Remove duplicate pick_random_edge_turf resulting from our simultaneous addition of it (in overmaps PR)
- Disable SSgame_master and SSevent_ticker subystems, we are still using the original events subsystem.
- Disable the game_master implementations as we are not using them.
- Comment out references to SSgame_master since we are not using it (yet?)
- Best practice to avoid holding onto references to the subsystem instances aside from the global variables. (In case of restart/recover etc).
- The reference to GM was entirely unused by any event or meta-event. /datum/game_master would work fine using the global refs.
