Added new RNDIS Host class driver and the beginnings of a RNDISEthernetHost Class Driver demo.

Fixed all Class drivers to ensure they have appropriate guards on each function to ensure the device is enumerated before running, fixed error codes on all guards to return "DeviceDisconnected" where possble.

Renamed HOST_SENDCONTROL_DeviceDisconnect enum value to HOST_SENDCONTROL_DeviceDisconnected to be in line with the rest of the library enum error codes.

Demos/Host/ClassDriver/makefile

@@ -41,6 +41,9 @@ all:
 	make -C PrinterHost clean
 	make -C PrinterHost all
 
+	make -C RNDISEthernetHost clean
+	make -C RNDISEthernetHost all
+
 	make -C StillImageHost clean
 	make -C StillImageHost all
 	
@@ -53,4 +56,5 @@ all:
 	make -C MouseHostWithParser $@
 	make -C MassStorageHost $@
 	make -C PrinterHost $@
+	make -C RNDISEthernetHost $@
 	make -C StillImageHost $@