mu3: added lights hook

mu3io/ledoutput.h

@@ -0,0 +1,20 @@
+/*
+    LED output functions
+    
+    Credits:
+    somewhatlurker, skogaby
+*/
+
+#pragma once
+
+#include <windows.h>
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "mu3io/config.h"
+
+extern HANDLE mu3_led_init_mutex;
+
+HRESULT mu3_led_output_init(struct mu3_io_config* const cfg);
+void mu3_led_output_update(int board, const byte* rgb);