Converts some istype's to use helpers (#3224)

Converts various istype's to use helpers. Mainly:
Cable
Wrench
Screwdriver
Multitool
Crowbar
Wirecutter

And makes the helpers defines.

code/modules/power/singularity/collector.dm

@@ -67,11 +67,11 @@ var/global/list/rad_collectors = list()
 		W.loc = src
 		update_icons()
 		return 1
-	else if(istype(W, /obj/item/weapon/crowbar))
+	else if(iscrowbar(W))
 		if(P && !src.locked)
 			eject()
 			return 1
-	else if(istype(W, /obj/item/weapon/wrench))
+	else if(iswrench(W))
 		if(P)
 			user << "<span class='notice'>Remove the phoron tank first.</span>"
 			return 1

code/modules/power/singularity/emitter.dm

@@ -151,7 +151,7 @@
 
 /obj/machinery/power/emitter/attackby(obj/item/W, mob/user)
 
-	if(istype(W, /obj/item/weapon/wrench))
+	if(iswrench(W))
 		if(active)
 			user << "Turn off [src] first."
 			return
@@ -174,7 +174,7 @@
 				user << "<span class='warning'>\The [src] needs to be unwelded from the floor.</span>"
 		return
 
-	if(istype(W, /obj/item/weapon/weldingtool))
+	if(iswelder(W))
 		var/obj/item/weapon/weldingtool/WT = W
 		if(active)
 			user << "Turn off [src] first."

code/modules/power/singularity/field_generator.dm

@@ -93,7 +93,7 @@ field_generator power level display
 	if(active)
 		user << "The [src] needs to be off."
 		return
-	else if(istype(W, /obj/item/weapon/wrench))
+	else if(iswrench(W))
 		switch(state)
 			if(0)
 				state = 1
@@ -112,7 +112,7 @@ field_generator power level display
 			if(2)
 				user << "<span class='warning'>The [src.name] needs to be unwelded from the floor.</span>"
 				return
-	else if(istype(W, /obj/item/weapon/weldingtool))
+	else if(iswelder(W))
 		var/obj/item/weapon/weldingtool/WT = W
 		switch(state)
 			if(0)

code/modules/power/singularity/generator.dm

@@ -17,7 +17,7 @@
 		if(src) qdel(src)
 
 /obj/machinery/the_singularitygen/attackby(obj/item/W, mob/user)
-	if(istype(W, /obj/item/weapon/wrench))
+	if(iswrench(W))
 		anchored = !anchored
 		playsound(src.loc, 'sound/items/Ratchet.ogg', 75, 1)
 		if(anchored)