Speeds up area power usage handling, and apc process(). Cleans up related code (#51002)

About The Pull Request

/area/proc/usage() attempts to give list-like access to a bunch of vars. Why not make it a list instead and avoid all the proc calls? Might be room for followup here, to do something to powered(), use_power() etc.

Some legacy machinery was ignoring the default machinery use_power pulling from the machine's power channel by default

Total power usage was unused, APCs ignored it in favor of calculating it themselves :)

I also renamed the defines because they were in the danger zone of being very common words.
Changelog

cl Naksu
code: optimized area power usage calculations.
/cl

code/modules/paperwork/photocopier.dm

@@ -16,7 +16,7 @@
 	use_power = IDLE_POWER_USE
 	idle_power_usage = 30
 	active_power_usage = 200
-	power_channel = EQUIP
+	power_channel = AREA_USAGE_EQUIP
 	max_integrity = 300
 	integrity_failure = 0.33
 	var/obj/item/paper/copy = null	//what's in the copier!
@@ -31,7 +31,7 @@
 
 /obj/machinery/photocopier/ui_interact(mob/user)
 	. = ..()
-	var/dat = "Photocopier<BR><BR>"
+	var/list/dat = list("Photocopier<BR><BR>")
 	if(copy || photocopy || doccopy || (ass && (ass.loc == src.loc)))
 		dat += "<a href='byond://?src=[REF(src)];remove=1'>Remove Paper</a><BR>"
 		if(toner)
@@ -48,7 +48,7 @@
 	dat += "Current toner level: [toner]"
 	if(!toner)
 		dat +="<BR>Please insert a new toner cartridge!"
-	user << browse(dat, "window=copier")
+	user << browse(dat.Join(""), "window=copier")
 	onclose(user, "copier")
 
 /obj/machinery/photocopier/Topic(href, href_list)