Log Message:
Update to 1.0.18.
Reanem hp3900 option to sane-backends-hp3900, and add legacy
handling for the old option name.

New with 1.0.18, released 2006-07-02:

* New backends: dell1600n_net (Dell 1600n), hp3500 (HP ScanJet 3500 series),
  pixma (Canon Pixma series), stv680 (Aiptek Pencam and similar).
* Updated backends: avision, canon, dll, epson, fujitsu, genesys, gt68xx,
  microtek2, mustek_pp, niash, plustek, snapscan, sp15c, test, u12, umax1220u.
* Scanimage batch mode fixes.
* Scanner lists contain USB vendor/product ids and some statistics now.
* Udev/hotplug lists are generated autmatically from the .desc files now.
* Portability fixes (especially for DragonFlyBSD and HP/UX).
* Build system updates.
* Updated translations.
* Documentation updates.
* Bugfixes.