Makes cable use BYOND directions

Instead of 11,12 they use 32,16 for DOWN,UP
Merges multiz handling into main logic
Port of: https://github.com/Baystation12/Baystation12/pull/15907

code/modules/multiz/basic.dm

@@ -43,3 +43,11 @@ var/z_levels = 0 // Each bit represents a connection between adjacent levels.  S
 
 proc/AreConnectedZLevels(var/zA, var/zB)
 	return zA == zB || (zB in GetConnectedZlevels(zA))
+
+/proc/get_zstep(ref, dir)
+	if(dir == UP)
+		. = GetAbove(ref)
+	else if (dir == DOWN)
+		. = GetBelow(ref)
+	else
+		. = get_step(ref, dir)

code/modules/power/cable.dm

@@ -376,25 +376,15 @@ obj/structure/cable/proc/cableColor(var/colorC)
 	. = list()	// this will be a list of all connected power objects
 	var/turf/T
 
-	// Handle up/down cables
-	if(d1 == 11 || d2 == 11)
-		T = GetBelow(src)
-		if(T)
-			. += power_list(T, src, 12, 1)
-	if(d1 == 12 || d1 == 12)
-		T = GetAbove(src)
-		if(T)
-			. += power_list(T, src, 11, 1)
-
 	// Handle standard cables in adjacent turfs
 	for(var/cable_dir in list(d1, d2))
-		if(cable_dir == 11 || cable_dir == 12 || cable_dir == 0)
+		if(cable_dir == 0)
 			continue
 		var/reverse = reverse_dir[cable_dir]
-		T = get_step(src, cable_dir)
+		T = get_zstep(src, cable_dir)
 		if(T)
 			for(var/obj/structure/cable/C in T)
-				if((C.d1 && C.d1 == reverse) || (C.d2 && C.d2 == reverse))
+				if(C.d1 == reverse || C.d2 == reverse)
 					. += C
 		if(cable_dir & (cable_dir - 1)) // Diagonal, check for /\/\/\ style cables along cardinal directions
 			for(var/pair in list(NORTH|SOUTH, EAST|WEST))
@@ -402,7 +392,7 @@ obj/structure/cable/proc/cableColor(var/colorC)
 				if(T)
 					var/req_dir = cable_dir ^ pair
 					for(var/obj/structure/cable/C in T)
-						if((C.d1 && C.d1 == req_dir) || (C.d2 && C.d2 == req_dir))
+						if(C.d1 == req_dir || C.d2 == req_dir)
 							. += C
 
 	// Handle cables on the same turf as us

code/modules/power/power.dm

@@ -209,16 +209,8 @@
 // if unmarked==1, only return those with no powernet
 /proc/power_list(var/turf/T, var/source, var/d, var/unmarked=0, var/cable_only = 0)
 	. = list()
-	var/fdir = (!d)? 0 : turn(d, 180)			// the opposite direction to d (or 0 if d==0)
+
-///// Z-Level Stuff
+	var/reverse = d ? reverse_dir[d] : 0
-	var/Zdir
-	if(d==11)
-		Zdir = 11
-	else if (d==12)
-		Zdir = 12
-	else
-		Zdir = 999
-///// Z-Level Stuff
 	for(var/AM in T)
 		if(AM == source)	continue			//we don't want to return source
 
@@ -234,11 +226,7 @@
 			var/obj/structure/cable/C = AM
 
 			if(!unmarked || !C.powernet)
-///// Z-Level Stuff
+				if(C.d1 == d || C.d2 == d || C.d1 == reverse || C.d2 == reverse )
-				if(C.d1 == fdir || C.d2 == fdir || C.d1 == Zdir || C.d2 == Zdir)
-///// Z-Level Stuff
-					. += C
-				else if(C.d1 == d || C.d2 == d)
 					. += C
 	return .