Lag War Day 4: Under Pressure, High Voltage (#21878)

Replace /datum/gas_mixture/proc/return_pressure with XGM_PRESSURE(xgm)
macro. Having such a relatively simple statement contributing proc
overhead to procs called millions of times is ridiculous

Rename /datum/gas_mixture/proc/zburn to react, deleting the old react
which was just an alias for it. Free proc overhead

Turn check_combustibility into a macro CHECK_COMBUSTIBLE(is_cmb, xgm).
also rewrite it slightly so that it only needs to do one pass. Its a bit
nasty so I apologize for that, but speeeeed.

Delete most powernet and obj/machinery/power procs for handling power,
replacing them with macros. The fact that we were unironically calling a
draw_power() on APCs to call draw_power() on their terminals to call
draw_power() on their powernet every single process tick was insane.

Turn `between` into a macro alias for clamp() since the param order is
different

turn `Percent` into a macro AS_PCT

Rewrite significant chunks of update_canmove so its not quite as
horrifying of a proc and hopefully doesn't eat the entire mob subsystem
every movement now

code/modules/spell_system/spells/spell_list/others/generic/mend.dm

@@ -47,7 +47,7 @@
 		user.visible_message(SPAN_NOTICE("\The [user] rests a hand on \the [target]'s [E.name]."))
 		to_chat(target, SPAN_NOTICE("A healing warmth suffuses you."))
 
-		for(var/datum/wound/W in E.wounds)
+		for(var/datum/wound/W as anything in E.wounds)
 			if(W.bleeding())
 				to_chat(user, SPAN_NOTICE("You knit together severed veins and broken flesh, stemming the bleeding."))
 				W.bleed_timer = 0