This patch adds additional vendor and product ids for Nikon, Mustek,
Plustek, Genius, Epson, Canon, Umax, Hewlett-Packard, Benq, Agfa,
and Minolta scanners. The entries for Benq, Genius and Plustek
scanners have been updated.

I've also increased the version number to 0.4.9 and brought the
version numbers in scanner.c and scanner.h in sync.