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/multiz/movement.dm

@@ -230,7 +230,7 @@
 	return 1
 
 /mob/living/silicon/robot/can_ztravel(var/direction)
-	if(incapacitated() || is_dead())
+	if(incapacitated() || (stat == DEAD))
 		return FALSE
 
 	if(Allow_Spacemove()) //Checks for active jetpack

code/modules/multiz/pipes.dm

@@ -74,7 +74,7 @@
 	if(!loc) return FALSE
 	var/datum/gas_mixture/environment = loc.return_air()
 
-	var/pressure_difference = pressure - environment.return_pressure()
+	var/pressure_difference = pressure - XGM_PRESSURE(environment)
 
 	if(pressure_difference > maximum_pressure)
 		burst()