Add new Audio Class Driver Host demos.

Fix errors in the new Audio Host mode Class Driver, which would have prevented data from being sent or received properly by the device.

Add microphone/square wave generation compile time switch to the Low Level AudioOutput Host demo.

LUFA/Drivers/USB/Class/Host/Audio.c

@@ -209,7 +209,7 @@ uint8_t Audio_GetSetEndpointProperty(USB_ClassInfo_Audio_Host_t* const AudioInte
 			                         const uint8_t EndpointProperty,
 			                         const uint8_t EndpointControl,
 			                         uint16_t const DataLength,
-			                         uint8_t* Data)
+			                         void* const Data)
 {
 	uint8_t RequestType;
 	uint8_t EndpointAddress;