Puts files in single quotes like they belong

This means they're included into the rsc and sent out althogh almost all of these files were already included elsewhere. Also DM will yell if the file couldn't be found for whatever reason like if someone moves or renames it.

I left out some file types for various reasons
dmis used in overlays: I have another pr I'll do later which will fix all of them and I don't want to conflict with myself
text files: they would get included in the rsc, which is completely unnecessary. However they're small, so they might be worth including anyway

code/game/objects/structures/displaycase.dm

@@ -73,7 +73,7 @@
 	if(alert)
 		var/area/alarmed = get_area(src)
 		alarmed.burglaralert(src)
-		playsound(src, "sound/effects/alert.ogg", 50, 1)
+		playsound(src, 'sound/effects/alert.ogg', 50, 1)
 
 /*
 

code/game/objects/structures/kitchen_spike.dm

@@ -81,7 +81,7 @@
 				return
 			if(user.pulling != L)
 				return
-			playsound(src.loc, "sound/effects/splat.ogg", 25, 1)
+			playsound(src.loc, 'sound/effects/splat.ogg', 25, 1)
 			L.visible_message("<span class='danger'>[user] slams [L] onto the meat spike!</span>", "<span class='userdanger'>[user] slams you onto the meat spike!</span>", "<span class='italics'>You hear a squishy wet noise.</span>")
 			L.loc = src.loc
 			L.emote("scream")