Ported Catwalks from Eris

* Catwalks are an upgrade to lattice; instead of just a framework of wires its a mostly solid grid walkway.
* They are semi-transparent so you can see wires/pipes below them a bit.
* Smoothly auto-joining sprites to look proper.
* Constructed by upgrading lattice; like lattice it will stop you falling if build over an open space.
* Changes from Eris: Converted << to to_chat(), fix redraw on Destroy(), Fix color macros in text.

code/game/objects/structures/catwalk.dm

@@ -0,0 +1,83 @@
+// Based on catwalk.dm from https://github.com/Endless-Horizon/CEV-Eris
+/obj/structure/catwalk
+	layer = TURF_LAYER + 0.5
+	icon = 'icons/turf/catwalks.dmi'
+	icon_state = "catwalk"
+	name = "catwalk"
+	desc = "Cats really don't like these things."
+	density = 0
+	anchored = 1.0
+
+/obj/structure/catwalk/New()
+	..()
+	spawn(4)
+		if(src)
+			for(var/obj/structure/catwalk/C in get_turf(src))
+				if(C != src)
+					qdel(C)
+			update_icon()
+			redraw_nearby_catwalks()
+
+/obj/structure/catwalk/Destroy()
+	..()
+	redraw_nearby_catwalks()
+
+/obj/structure/catwalk/proc/redraw_nearby_catwalks()
+	for(var/direction in alldirs)
+		if(locate(/obj/structure/catwalk, get_step(src, direction)))
+			var/obj/structure/catwalk/L = locate(/obj/structure/catwalk, get_step(src, direction))
+			L.update_icon() //so siding get updated properly
+
+
+/obj/structure/catwalk/update_icon()
+	var/connectdir = 0
+	for(var/direction in cardinal)
+		if(locate(/obj/structure/catwalk, get_step(src, direction)))
+			connectdir |= direction
+
+	//Check the diagonal connections for corners, where you have, for example, connections both north and east. In this case it checks for a north-east connection to determine whether to add a corner marker or not.
+	var/diagonalconnect = 0 //1 = NE; 2 = SE; 4 = NW; 8 = SW
+	//NORTHEAST
+	if(connectdir & NORTH && connectdir & EAST)
+		if(locate(/obj/structure/catwalk, get_step(src, NORTHEAST)))
+			diagonalconnect |= 1
+	//SOUTHEAST
+	if(connectdir & SOUTH && connectdir & EAST)
+		if(locate(/obj/structure/catwalk, get_step(src, SOUTHEAST)))
+			diagonalconnect |= 2
+	//NORTHWEST
+	if(connectdir & NORTH && connectdir & WEST)
+		if(locate(/obj/structure/catwalk, get_step(src, NORTHWEST)))
+			diagonalconnect |= 4
+	//SOUTHWEST
+	if(connectdir & SOUTH && connectdir & WEST)
+		if(locate(/obj/structure/catwalk, get_step(src, SOUTHWEST)))
+			diagonalconnect |= 8
+
+	icon_state = "catwalk[connectdir]-[diagonalconnect]"
+
+
+/obj/structure/catwalk/ex_act(severity)
+	switch(severity)
+		if(1.0)
+			qdel(src)
+		if(2.0)
+			qdel(src)
+	return
+
+/obj/structure/catwalk/attackby(obj/item/C as obj, mob/user as mob)
+	if (istype(C, /obj/item/weapon/weldingtool))
+		var/obj/item/weapon/weldingtool/WT = C
+		if(WT.isOn())
+			if(WT.remove_fuel(0, user))
+				to_chat(user, "<span class='notice'>Slicing lattice joints ...</span>")
+				PoolOrNew(/obj/item/stack/rods, src.loc)
+				PoolOrNew(/obj/item/stack/rods, src.loc)
+				PoolOrNew(/obj/structure/lattice, src.loc)
+				qdel(src)
+	return ..()
+
+/obj/structure/catwalk/Crossed()
+	. = ..()
+	if(isliving(usr))
+		playsound(src, pick('sound/effects/footstep/catwalk1.ogg', 'sound/effects/footstep/catwalk2.ogg', 'sound/effects/footstep/catwalk3.ogg', 'sound/effects/footstep/catwalk4.ogg', 'sound/effects/footstep/catwalk5.ogg'), 25, 1)

code/game/objects/structures/lattice.dm

@@ -67,7 +67,16 @@
 				user << "<span class='notice'>Slicing lattice joints ...</span>"
 			PoolOrNew(/obj/item/stack/rods, src.loc)
 			qdel(src)
-
+		return
+	if (istype(C, /obj/item/stack/rods))
+		var/obj/item/stack/rods/R = C
+		if(R.use(2))
+			user << "<span class='notice'>You start connecting \the [R.name] to \the [src.name] ...</span>"
+			if(do_after(user, 5 SECONDS))
+				src.alpha = 0 // Note: I don't know why this is set, Eris did it, just trusting for now. ~Leshana
+				PoolOrNew(/obj/structure/catwalk, src.loc)
+				qdel(src)
+		return
 	return
 
 /obj/structure/lattice/proc/updateOverlays()