Changes all cases of update_icons(), updateicon(), UpdateIcon() etc. to update_icon(). (#9432)

update_icons(), UpdateIcon() and updateicon() are now changed to be update_icon().

Many interactions expect a target to have an update_icon(), so they should all be the same.

Also fixed some stuff that was using relative pathing, along the way.

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

@@ -390,7 +390,7 @@
 	else
 		to_chat(usr, "<span class='warning'>This mob type can't use this verb.</span>")
 
-/obj/structure/closet/update_icon()//Putting the welded stuff in updateicon() so it's easy to overwrite for special cases (Fridges, cabinets, and whatnot)
+/obj/structure/closet/update_icon()//Putting the welded stuff in update_icon() so it's easy to overwrite for special cases (Fridges, cabinets, and whatnot)
 	cut_overlays()
 	if(!opened)
 		icon_state = icon_closed

code/game/objects/structures/crates_lockers/closets/secure/secure_closets.dm

@@ -235,7 +235,7 @@
 	else
 		to_chat(usr, "<span class='warning'>This mob type can't use this verb.</span>")
 
-/obj/structure/closet/secure_closet/update_icon()//Putting the welded stuff in updateicon() so it's easy to overwrite for special cases (Fridges, cabinets, and whatnot)
+/obj/structure/closet/secure_closet/update_icon()//Putting the welded stuff in update_icon() so it's easy to overwrite for special cases (Fridges, cabinets, and whatnot)
 	cut_overlays()
 	if(!opened)
 		if(locked)

code/game/objects/structures/watercloset.dm

@@ -325,7 +325,7 @@
 			M.clean_blood()
 
 		if (update_icons_required)
-			M.update_icons()
+			M.update_icon()
 	else
 		O.clean_blood()