USB_HostRequest renamed to USB_ControlRequest, entire control request header...

USB_HostRequest renamed to USB_ControlRequest, entire control request header is now read into USB_ControlRequest in Device mode rather than having the library pass only partially read header data to the application.

The USB_UnhandledControlPacket event has had its parameters removed, in favour of accessing the new USB_ControlRequest structure.

The Endpoint control stream functions now correctly send a ZLP to the host when less data than requested is sent.