Adds a cursed sword (and other haunted things) (#4931)

* adds cursed sword and 'haunted' object framework.

* fixes back.dmi conflicts

* adds cursed blade ghost pod

as well as fixing some ghost pod oddities

* fixes misc.dm conflicts

* adds cursed sword cave POI

* makes cursed sword use voice mob

as opposed to a brainmob

code/modules/mob/living/carbon/brain/MMI.dm

@@ -6,6 +6,7 @@
 	icon = 'icons/obj/assemblies.dmi'
 	icon_state = "mmi_empty"
 	w_class = ITEMSIZE_NORMAL
+	can_speak = 1
 	origin_tech = list(TECH_BIO = 3)
 
 	req_access = list(access_robotics)

code/modules/mob/living/carbon/brain/say.dm

@@ -5,8 +5,8 @@
 
 	message = sanitize(message)
 
-	if(!(container && istype(container, /obj/item/device/mmi)))
-		return //No MMI, can't speak, bucko./N
+	if(!(container && container.can_speak))
+		return //Certain objects can speak, like MMIs. Most others cannot. -Q
 	else
 		var/datum/language/speaking = parse_language(message)
 		if(speaking)