Unifies datum var definitions (#2237)

code/controllers/subsystem/garbage.dm

@@ -234,33 +234,7 @@ SUBSYSTEM_DEF(garbage)
 	else if(D.gc_destroyed == GC_CURRENTLY_BEING_QDELETED)
 		CRASH("[D.type] destroy proc was called multiple times, likely due to a qdel loop in the Destroy logic")
 
-// Default implementation of clean-up code.
-// This should be overridden to remove all references pointing to the object being destroyed.
-// Return the appropriate QDEL_HINT; in most cases this is QDEL_HINT_QUEUE.
-// TODO: Move this and all datum var definitions into code/datums/datum.dm
-/datum/proc/Destroy(force=FALSE)
-	tag = null
-	var/list/timers = active_timers
-	active_timers = null
-	for(var/thing in timers)
-		var/datum/timedevent/timer = thing
-		if (timer.spent)
-			continue
-		qdel(timer)
-	var/list/dc = datum_components
-	for(var/I in dc)
-		var/datum/component/C = I
-		C._RemoveNoSignal()
-		qdel(C)
-	if(dc)
-		dc.Cut()
-	return QDEL_HINT_QUEUE
-
-/datum/var/gc_destroyed //Time when this object was destroyed.
-
 #ifdef TESTING
-/datum/var/running_find_references
-/datum/var/last_find_references = 0
 
 /datum/verb/find_refs()
 	set category = "Debug"

code/controllers/subsystem/timer.dm

@@ -210,7 +210,6 @@ SUBSYSTEM_DEF(timer)
 	timer_id_dict |= SStimer.timer_id_dict
 	bucket_list |= SStimer.bucket_list
 
-/datum/var/list/active_timers
 /datum/timedevent
 	var/id
 	var/datum/callback/callBack

code/datums/components/component.dm

@@ -66,8 +66,6 @@
 /datum/component/proc/OnTransfer(datum/new_parent)
 	return
 
-/datum/var/list/datum_components //list of /datum/component
-
 /datum/proc/SendSignal(sigtype, ...)
 	var/list/comps = datum_components
 	. = FALSE

code/datums/datum.dm

@@ -0,0 +1,31 @@
+/datum
+    var/gc_destroyed //Time when this object was destroyed.
+    var/list/active_timers  //for SStimer
+    var/list/datum_components //for /datum/components
+    var/ui_screen = "home"  //for tgui
+
+#ifdef TESTING
+    var/running_find_references
+    var/last_find_references = 0
+#endif
+
+// Default implementation of clean-up code.
+// This should be overridden to remove all references pointing to the object being destroyed.
+// Return the appropriate QDEL_HINT; in most cases this is QDEL_HINT_QUEUE.
+/datum/proc/Destroy(force=FALSE)
+	tag = null
+	var/list/timers = active_timers
+	active_timers = null
+	for(var/thing in timers)
+		var/datum/timedevent/timer = thing
+		if (timer.spent)
+			continue
+		qdel(timer)
+	var/list/dc = datum_components
+	for(var/I in dc)
+		var/datum/component/C = I
+		C._RemoveNoSignal()
+		qdel(C)
+	if(dc)
+		dc.Cut()
+	return QDEL_HINT_QUEUE

code/modules/tgui/external.dm

@@ -60,13 +60,6 @@
 /datum/proc/ui_host()
 	return src // Default src.
 
- /**
-  * global
-  *
-  * Used to track the current screen.
- **/
-/datum/var/ui_screen = "home"
-
  /**
   * global
   *