[sane-devel] genesys backend update

[stef]

	Hello,

	I have committed an update to the genesys backend which brings the following 
features for gl646 based scanners:
	- shading calibration fix leading to much improved scan quality over previous
	  releases.
	- shading calibration for sheet-fed scanners, tested on the XP200.

	Known bugs are:
	- first scan after sheet-fed calibration doesn't load document properly.
	- first scan with motor resolution is higher than max sensor resolution is    
	  black after calibration.

Regards,
	Stef