Add more include protection macros to give the user warnings when they try to manually include private driver header files, instead of the public driver headers.

LUFA/Drivers/USB/Class/Device/MIDI.h

@@ -47,7 +47,6 @@
 	/* Includes: */
 		#include "../../USB.h"
 		#include "../Common/MIDI.h"
-		#include "Audio.h"
 
 		#include <string.h>
 
@@ -56,6 +55,11 @@
 			extern "C" {
 		#endif
 
+	/* Preprocessor Checks: */
+		#if !defined(__INCLUDE_FROM_MIDI_DRIVER)
+			#error Do not include this file directly. Include LUFA/Drivers/Class/MIDI.h instead.
+		#endif
+
 	/* Public Interface - May be used in end-application: */
 		/* Type Define: */
 			/** Class state structure. An instance of this structure should be made for each MIDI interface