Overview of changes in simple-scan 3.34.6

  * Don't prompt to save if nothing to save.
  * Use default quality setting to prevent slow scanning.
  * Don't interrupt scanning if the device is busy.
  * Fix size of first page on second scan.
  * Support saving files to FUSE file systems.
  * Improve handling and debugging of inactive SANE options.
  * Use fast scan mode on brother scanners.
  * Add initial Lexmark printers support.
  * Fix setting source for Epson scanner.
  * Add ADF duplex support for Brother DS-720.
  * Update known USB scanner IDs.