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/Common/Audio.h

@@ -51,6 +51,11 @@
 			extern "C" {
 		#endif
 
+	/* Preprocessor Checks: */
+		#if !defined(__INCLUDE_FROM_AUDIO_DRIVER)
+			#error Do not include this file directly. Include LUFA/Drivers/Class/Audio.h instead.
+		#endif
+
 	/* Macros: */
 		#if !defined(AUDIO_TOTAL_SAMPLE_RATES) || defined(__DOXYGEN__)
 			/** Total number of discrete audio sample rates supported by the device. This value can be overridden by defining this

LUFA/Drivers/USB/Class/Common/CDC.h

@@ -51,6 +51,11 @@
 			extern "C" {
 		#endif
 
+	/* Preprocessor Checks: */
+		#if !defined(__INCLUDE_FROM_CDC_DRIVER)
+			#error Do not include this file directly. Include LUFA/Drivers/Class/CDC.h instead.
+		#endif
+		
 	/* Macros: */
 		/** CDC Class specific request to get the current virtual serial port configuration settings. */
 		#define REQ_GetLineEncoding              0x21

LUFA/Drivers/USB/Class/Common/HID.h

@@ -46,6 +46,11 @@
 
 		#include <string.h>
 
+	/* Preprocessor Checks: */
+		#if !defined(__INCLUDE_FROM_HID_DRIVER)
+			#error Do not include this file directly. Include LUFA/Drivers/Class/HID.h instead.
+		#endif
+		
 	/* Macros: */
 		/** HID Class Specific Request to get the current HID report from the device. */
 		#define REQ_GetReport                   0x01

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

@@ -41,6 +41,9 @@
 #ifndef _MIDI_CLASS_COMMON_H_
 #define _MIDI_CLASS_COMMON_H_
 
+	/* Macros: */
+		#define __INCLUDE_FROM_AUDIO_DRIVER
+
 	/* Includes: */
 		#include "../../USB.h"
 		#include "Audio.h"
@@ -52,6 +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
+		
 	/* Macros: */
 		/** Audio class descriptor subtype value for a Audio class specific MIDI input jack descriptor. */
 		#define DSUBTYPE_InputJack          0x02

LUFA/Drivers/USB/Class/Common/MassStorage.h

@@ -51,6 +51,11 @@
 			extern "C" {
 		#endif
 
+	/* Preprocessor Checks: */
+		#if !defined(__INCLUDE_FROM_MS_DRIVER)
+			#error Do not include this file directly. Include LUFA/Drivers/Class/MassStorage.h instead.
+		#endif
+		
 	/* Macros: */
 		/** Mass Storage Class specific request to reset the Mass Storage interface, ready for the next command. */
 		#define REQ_MassStorageReset       0xFF

LUFA/Drivers/USB/Class/Common/Printer.h

@@ -49,8 +49,13 @@
 	/* Enable C linkage for C++ Compilers: */
 		#if defined(__cplusplus)
 			extern "C" {
-		#endif
+		#endif
 
+	/* Preprocessor Checks: */
+		#if !defined(__INCLUDE_FROM_PRINTER_DRIVER)
+			#error Do not include this file directly. Include LUFA/Drivers/Class/Printer.h instead.
+		#endif
+		
 	/* Macros: */
 		/** Port status mask for a printer device, indicating that an error has *not* occurred. */
 		#define PRNT_PORTSTATUS_NOTERROR    (1 << 3)

LUFA/Drivers/USB/Class/Common/RNDIS.h

@@ -41,10 +41,13 @@
 #ifndef _RNDIS_CLASS_COMMON_H_
 #define _RNDIS_CLASS_COMMON_H_
 
+	/* Macros: */
+		#define __INCLUDE_FROM_CDC_DRIVER
+
 	/* Includes: */
 		#include "../../USB.h"
-		#include "CDC.h"
 		#include "RNDISConstants.h"
+		#include "CDC.h"
 		
 		#include <string.h>
 	
@@ -53,6 +56,11 @@
 			extern "C" {
 		#endif
 
+	/* Preprocessor Checks: */
+		#if !defined(__INCLUDE_FROM_RNDIS_DRIVER)
+			#error Do not include this file directly. Include LUFA/Drivers/Class/RNDIS.h instead.
+		#endif
+		
 	/* Macros: */
 		/** Implemented RNDIS Version Major */
 		#define REMOTE_NDIS_VERSION_MAJOR             0x01

LUFA/Drivers/USB/Class/Common/StillImage.h

@@ -51,6 +51,11 @@
 			extern "C" {
 		#endif
 
+	/* Preprocessor Checks: */
+		#if !defined(__INCLUDE_FROM_SI_DRIVER)
+			#error Do not include this file directly. Include LUFA/Drivers/Class/StillImage.h instead.
+		#endif
+		
 	/* Macros: */
 		/** Length in bytes of a given Unicode string's character length
 		 *