Defining Part 1 - Code cleanup toward defines (#19262)

* This is only the beginning

* Update stack.dm

code/modules/antagonists/changeling/powers/mutations.dm

@@ -275,7 +275,7 @@
 	if(blocked >= 100)
 		return 0
 	var/mob/living/carbon/human/H = firer
-	if(istype(target, /obj/item))
+	if(isitem(target))
 		var/obj/item/I = target
 		if(!I.anchored)
 			to_chat(firer, "<span class='notice'>You pull [I] towards yourself.</span>")
@@ -472,7 +472,7 @@
 
 	var/obj/item/I = hitby
 
-	if(!istype(I.loc, /mob/living))
+	if(!isliving(I.loc))
 		// Maybe it's on the ground? Maybe it's being used telekinetically? IDK
 		return
 

code/modules/antagonists/vampire/vamp_datum.dm

@@ -263,7 +263,7 @@
 			hud.show_hud(hud.hud_version)
 		hud.vampire_blood_display.maptext = "<div align='center' valign='middle' style='position:relative; top:0px; left:6px'><font face='Small Fonts' color='#ce0202'>[bloodusable]</font></div>"
 	handle_vampire_cloak()
-	if(istype(get_turf(owner.current), /turf/space))
+	if(isspaceturf(get_turf(owner.current)))
 		check_sun()
 	if(istype(get_area(owner.current), /area/chapel) && !get_ability(/datum/vampire_passive/full))
 		vamp_burn(7)