Fixes #11263.

Now possible to use items other than emags on holodeck computers
Blobs no longer make computers lose their density state.
Holodeck computers can now be repaired (and built, but since they cannot be configured they'll be useless).
Fixes #11263.

code/game/objects/items/weapons/circuitboards/computer/holodeckcontrol.dm

@@ -0,0 +1,31 @@
+#ifndef T_BOARD
+#error T_BOARD macro is not defined but we need it!
+#endif
+
+/obj/item/weapon/circuitboard/holodeckcontrol
+	name = T_BOARD("holodeck control console")
+	build_path = /obj/machinery/computer/HolodeckControl
+	origin_tech = "programming=2;bluespace=2"
+	var/last_to_emag
+	var/linkedholodeck_area
+	var/list/supported_programs
+	var/list/restricted_programs
+
+/obj/item/weapon/circuitboard/holodeckcontrol/construct(var/obj/machinery/computer/HolodeckControl/HC)
+	if (..(HC))
+		HC.supported_programs	= supported_programs.Copy()
+		HC.restricted_programs	= restricted_programs.Copy()
+		if(linkedholodeck_area)
+			HC.linkedholodeck	= locate(linkedholodeck_area)
+		if(last_to_emag)
+			HC.last_to_emag		= last_to_emag
+			HC.emagged 			= 1
+			HC.safety_disabled	= 1
+
+/obj/item/weapon/circuitboard/holodeckcontrol/deconstruct(var/obj/machinery/computer/HolodeckControl/HC)
+	if (..(HC))
+		linkedholodeck_area		= HC.linkedholodeck_area
+		supported_programs		= HC.supported_programs.Copy()
+		restricted_programs 	= HC.restricted_programs.Copy()
+		last_to_emag			= HC.last_to_emag
+		HC.emergencyShutdown()