[sane-devel] gt68xx backend update

[stef]

	Hello,

	thanks for an hardware donation of Jack McGill, I have been able to work on 
the gt68xx backend to bring calibration for sheetfed scanners. This work is 
now completed. I have tested on an OptisSlim M12. I have also enabled 
calibration for the Iriscan Express 2 and the ColorPage SF600. These 2 
scanners need to be tested.
	
	The only bug known is that 200 dpi scans still don't work, like it was before 
my work.

	If I eventually found how buttons work, I'll may add support for them.

Regards,
	Stef