Allow more freedom when replacing repeaters.
Have drills require a close power source. Reduce its cost 21 → 10.
Power down drill if there is no close power source.
Remove G_ prefix for static functions in g_buildable.c.
Merge branch 'gameplay/master' into gameplay/viech

Conflicts:
	src/gamelogic/game/g_buildable.c
Merge branch 'gameplay/viech' into bots+viech

Conflicts:
	src/gamelogic/game/g_buildable.c
	src/gamelogic/game/g_local.h