USB_IsConnected is now cleared before the USB_Disconnect() event is fired in response to VBUS being removed.

Minor documentation improvements.

Fixed incorrect ENDPOINT_EPNUM_MASK mask preventing endpoints above EP3 from being selected (thanks to Jonathan Oakley).

Removed STREAM_CALLBACK() macro - callbacks now use regular function definitions to clarify user code.

Removed DESCRIPTOR_COMPARATOR() macro - comparators should now use regular function definitions to clarify user code.

Removed all user pipe/endpoint interrupt APIs, added internal library support for interrupt driven control endpoints when in device mode by defining INTERRUPT_CONTROL_ENDPOINT token and passing it to the compiler via the -D switch.

Move StdRequestType.h, StreamCallbacks.h, USBMode.h from the LowLevel USB driver directory to the HighLevel USB driver directory, where they are more suited.