Destroy() cleanups in VOREStation code

* Remove remaining hard del()'s in our code.
* Replace deleted() and gcDestroyed with QDELETED macro.
* Fix some strange calls directly to Del() (capital D)
* Make Destroy() return qdel hints.
* Make a few of the Destroy()'s more comprehensive in cleaning up references.
* In edited Destroy() procs, converted to use qdel_null and qdel_null_list macros when possible for pretty code.
* Removed unused variable `sleevecard`

code/modules/nifsoft/software/05_health.dm

@@ -12,8 +12,8 @@
 		arscreen = new(nif)
 
 	Destroy()
-		qdel(arscreen)
-		..()
+		qdel_null(arscreen)
+		return ..()
 
 	activate()
 		if((. = ..()))

code/modules/nifsoft/software/13_soulcatcher.dm

@@ -25,11 +25,8 @@
 		load_settings()
 
 	Destroy()
-		for(var/brain in brainmobs)
-			var/mob/living/carbon/brain/caught_soul/CS = brain
-			qdel(CS)
-		brainmobs.Cut()
-		..()
+		qdel_null_list(brainmobs)
+		return ..()
 
 	install()
 		if((. = ..()))
@@ -249,10 +246,8 @@
 		soulcatcher = null
 	if(nif)
 		nif = null
-	if(mind && ckey)
-		src.ghostize()
 	container = null
-	..()
+	return ..()
 
 /mob/living/carbon/brain/caught_soul/Life()
 	if(!mind)

code/modules/nifsoft/software/14_commlink.dm

@@ -43,13 +43,14 @@
 		nif = newloc
 		nifsoft = soft
 		register_device(nif.human)
-		qdel(camera) //Not supported on internal one.
+		qdel_null(camera) //Not supported on internal one.
 
 	Destroy()
 		if(nif)
 			nif.comm = null
 			nif = null
-		..()
+		nifsoft = null
+		return ..()
 
 //So that only the owner's chat is relayed to others.
 /obj/item/device/communicator/commlink/hear_talk(mob/living/M, text, verb, datum/language/speaking)