Ports the VV Refactor by Kevinz.

code/modules/admin/view_variables/mark_datum.dm

@@ -0,0 +1,12 @@
+/client/proc/mark_datum(datum/D)
+	if(!holder)
+		return
+	if(holder.marked_datum)
+		vv_update_display(holder.marked_datum, "marked", "")
+	holder.marked_datum = D
+	vv_update_display(D, "marked", VV_MSG_MARKED)
+
+/client/proc/mark_datum_mapview(datum/D as mob|obj|turf|area in view(view))
+	set category = "Debug"
+	set name = "Mark Object"
+	mark_datum(D)