Ports Nano UI to Subsystems

code/controllers/subsystem/nanoui.dm

@@ -0,0 +1,33 @@
+SUBSYSTEM_DEF(nanoui)
+	name = "nanoui"
+	wait = 9
+	flags = SS_NO_INIT
+	priority = FIRE_PRIORITY_NANOUI
+	runlevels = RUNLEVEL_LOBBY | RUNLEVELS_DEFAULT
+
+	var/list/currentrun = list()
+	var/list/open_uis = list() // A list of open UIs, grouped by src_object and ui_key.
+	var/list/processing_uis = list() // A list of processing UIs, ungrouped.
+
+/datum/controller/subsystem/nanoui/Shutdown()
+	close_all_uis()
+
+/datum/controller/subsystem/nanoui/stat_entry()
+	..("P:[processing_uis.len]")
+
+/datum/controller/subsystem/nanoui/fire(resumed = 0)
+	if(!resumed)
+		src.currentrun = processing_uis.Copy()
+	//cache for sanic speed (lists are references anyways)
+	var/list/currentrun = src.currentrun
+
+	while(currentrun.len)
+		var/datum/nanoui/ui = currentrun[currentrun.len]
+		currentrun.len--
+		if(ui && ui.user && ui.src_object)
+			ui.process()
+		else
+			processing_uis.Remove(ui)
+		if(MC_TICK_CHECK)
+			return
+