Small map, and sprite fixes. Welder fixes (#3887)

Fixed fire alarm in virology #3875

Fixed random pixel on glasses #3872

Fixed welder issue #3888. Plus explored further issue with welder, fixing it. Small logic optimization.

Fixed firelocker icon not being updated with welded overlay, even so they have been welded

Welding interaction with closets was reworked, almost all secure closets except for detective's, barternder's now work with welding same way as closets/crates.

Coffins, and wooden closets of any kind can no longer be welded shut.

Clean up of some code using src as reference, and :

code/game/objects/structures/crates_lockers/crates.dm

@@ -23,9 +23,9 @@
 	return 1
 
 /obj/structure/closet/crate/open()
-	if(src.opened)
+	if(opened)
 		return 0
-	if(!src.can_open())
+	if(!can_open())
 		return 0
 
 	if(rigged && locate(/obj/item/device/radio/electropack) in src)
@@ -36,7 +36,7 @@
 				if(usr.stunned)
 					return 2
 
-	playsound(src.loc, 'sound/machines/click.ogg', 15, 1, -3)
+	playsound(loc, 'sound/machines/click.ogg', 15, 1, -3)
 	for(var/obj/O in src)
 		O.forceMove(get_turf(src))
 
@@ -51,17 +51,17 @@
 			M.visible_message(span("danger","\The [M.name] tumbles out of the [src]!"))
 
 	icon_state = icon_opened
-	src.opened = 1
+	opened = 1
 	pass_flags = 0
 	return 1
 
 /obj/structure/closet/crate/close()
-	if(!src.opened)
+	if(!opened)
 		return 0
-	if(!src.can_close())
+	if(!can_close())
 		return 0
 
-	playsound(src.loc, 'sound/machines/click.ogg', 15, 1, -3)
+	playsound(loc, 'sound/machines/click.ogg', 15, 1, -3)
 	var/itemcount = 0
 	for(var/obj/O in get_turf(src))
 		if(itemcount >= storage_capacity)
@@ -76,7 +76,7 @@
 		itemcount++
 
 	icon_state = icon_closed
-	src.opened = 0
+	opened = 0
 	pass_flags = PASSTABLE//Crates can only slide under tables when closed
 	return 1
 
@@ -122,7 +122,7 @@
 
 	if (health <= 0)
 		for (var/atom/movable/A as mob|obj in src)
-			A.forceMove(src.loc)
+			A.forceMove(loc)
 			if (prob(50) && severity > 1)//Higher chance of breaking contents
 				A.ex_act(severity-1)
 			else
@@ -286,13 +286,13 @@
 		return !locked
 
 /obj/structure/closet/crate/secure/proc/togglelock(mob/user as mob)
-	if(src.opened)
+	if(opened)
 		user << "<span class='notice'>Close the crate first.</span>"
 		return
-	if(src.broken)
+	if(broken)
 		user << "<span class='warning'>The crate appears to be broken.</span>"
 		return
-	if(src.allowed(user))
+	if(allowed(user))
 		set_locked(!locked, user)
 		return 1
 	else
@@ -317,17 +317,17 @@
 		return
 
 	if(ishuman(usr))
-		src.add_fingerprint(usr)
-		src.togglelock(usr)
+		add_fingerprint(usr)
+		togglelock(usr)
 	else
 		usr << "<span class='warning'>This mob type can't use this verb.</span>"
 
 /obj/structure/closet/crate/secure/attack_hand(mob/user as mob)
-	src.add_fingerprint(user)
+	add_fingerprint(user)
 	if(locked)
-		return src.togglelock(user)
+		return togglelock(user)
 	else
-		return src.toggle(user)
+		return toggle(user)
 
 /obj/structure/closet/crate/secure/attackby(obj/item/weapon/W as obj, mob/user as mob)
 	if(is_type_in_list(W, list(/obj/item/weapon/packageWrap, /obj/item/stack/cable_coil, /obj/item/device/radio/electropack, /obj/item/weapon/wirecutters)))
@@ -335,7 +335,7 @@
 	if(istype(W, /obj/item/weapon/melee/energy/blade))
 		emag_act(INFINITY, user)
 	if(!opened)
-		src.togglelock(user)
+		togglelock(user)
 		return
 	return ..()
 
@@ -345,9 +345,9 @@
 		add_overlay(emag)
 		add_overlay(sparks)
 		CUT_OVERLAY_IN(sparks, 6)
-		playsound(src.loc, "sparks", 60, 1)
-		src.locked = 0
-		src.broken = 1
+		playsound(loc, "sparks", 60, 1)
+		locked = 0
+		broken = 1
 		user << "<span class='notice'>You unlock \the [src].</span>"
 		return 1
 
@@ -356,7 +356,7 @@
 		O.emp_act(severity)
 	if(!broken && !opened  && prob(50/severity))
 		if(!locked)
-			src.locked = 1
+			locked = 1
 			cut_overlays()
 			add_overlay(redlight)
 		else
@@ -364,14 +364,14 @@
 			add_overlay(emag)
 			add_overlay(sparks)
 			CUT_OVERLAY_IN(sparks, 6)
-			playsound(src.loc, 'sound/effects/sparks4.ogg', 75, 1)
-			src.locked = 0
+			playsound(loc, 'sound/effects/sparks4.ogg', 75, 1)
+			locked = 0
 	if(!opened && prob(20/severity))
 		if(!locked)
 			open()
 		else
-			src.req_access = list()
-			src.req_access += pick(get_all_station_access())
+			req_access = list()
+			req_access += pick(get_all_station_access())
 	..()
 
 /obj/structure/closet/crate/plastic
@@ -569,7 +569,7 @@
 	. = ..()
 	if (.)//we can hold up to one large item
 		var/found = 0
-		for(var/obj/structure/S in src.loc)
+		for(var/obj/structure/S in loc)
 			if(S == src)
 				continue
 			if(!S.anchored)
@@ -577,7 +577,7 @@
 				S.forceMove(src)
 				break
 		if(!found)
-			for(var/obj/machinery/M in src.loc)
+			for(var/obj/machinery/M in loc)
 				if(!M.anchored)
 					M.forceMove(src)
 					break
@@ -598,7 +598,7 @@
 	. = ..()
 	if (.)//we can hold up to one large item
 		var/found = 0
-		for(var/obj/structure/S in src.loc)
+		for(var/obj/structure/S in loc)
 			if(S == src)
 				continue
 			if(!S.anchored)
@@ -606,7 +606,7 @@
 				S.forceMove(src)
 				break
 		if(!found)
-			for(var/obj/machinery/M in src.loc)
+			for(var/obj/machinery/M in loc)
 				if(!M.anchored)
 					M.forceMove(src)
 					break
@@ -675,8 +675,8 @@
 	quantity = _quantity
 
 	spawntypes = list(
-		"1" = STOCK_RARE_PROB * rarity, 
-		"2" = STOCK_UNCOMMON_PROB * rarity, 
+		"1" = STOCK_RARE_PROB * rarity,
+		"2" = STOCK_UNCOMMON_PROB * rarity,
 		"3" = (100 - ((STOCK_RARE_PROB * rarity) + (STOCK_UNCOMMON_PROB * rarity)))
 	)