I just made a release of package 'backend'.
It contains mostly just the files needed for the
sane-backend with some filename and function changes.
The plugin-mechanism to support multiple types of USB transfer
mechanism has been removed and replaced by the sanei_usb functions
provided internally by the sane package. These functions already
implement access to both the scanner kernel module and libusb,
thereby obsoleting our own plugin-mechanism.
I hope this doesn't hurt the BSD people too much (but they can still
use libusb through sane)
I'm planning to submit this package to the SANE people and let
them have a look at it as a candidate for inclusion into SANE.