Added new USB_DeviceState variable to keep track of the current Device mode USB state.

Added new Endpoint_ClearStatusStage() convenience function to assist with the status stages of control transfers.

Removed vague USB_IsConnected global - test USB_DeviceState or USB_HostState explicitly to gain previous functionality.

Removed USB_IsSuspended global - test USB_DeviceState against DEVICE_STATE_Suspended instead.

Fixed possible enumeration errors from spinloops which may fail to exit if the USB connection is severed before the exit condition becomes true.

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

@@ -50,8 +50,7 @@ void Audio_Device_ProcessControlPacket(USB_ClassInfo_Audio_Device_t* const Audio
 				
 				AudioInterfaceInfo->State.InterfaceEnabled = (USB_ControlRequest.wValue != 0);
 				  
-				while (!(Endpoint_IsINReady()));
-				Endpoint_ClearIN();
+				Endpoint_ClearStatusStage();
 			}
 
 			break;