Add new MIDI Host Class driver to the library, and new MIDIHost ClassDriver demo.

Make MouseHost and KeyboardHost ClassDriver demos use the HID Class driver's structures for the boot protocol Mouse/Keyboard report data, rather than rolling their own.

LUFA/Drivers/USB/Class/MIDI.h

@@ -34,6 +34,7 @@
  *  \section Sec_Dependencies Module Source Dependencies
  *  The following files must be built with any user project that uses this module:
  *    - LUFA/Drivers/USB/Class/Device/MIDI.c
+ *    - LUFA/Drivers/USB/Class/Host/MIDI.c
  *
  *  \section Module Description
  *  MIDI Class Driver module. This module contains an internal implementation of the USB MIDI Class, for both Device
@@ -58,6 +59,10 @@
 		#if defined(USB_CAN_BE_DEVICE)
 			#include "Device/MIDI.h"
 		#endif
+
+		#if defined(USB_CAN_BE_HOST)
+			#include "Host/MIDI.h"
+		#endif
 		
 #endif