TODO list to be more KDE compliant:

TODO list of new features:

* Progressive final scan: scan can provide huge image especially in 16 bits color depth.
Send image data to host application by block, not the whole image at once.
* Use QGraphicsView for the preview (check Darkroom implementation)
* Test the batch scanning.
* Be more verbose about errors (why did sane_open fail...)
* Rework Scanner selection dialog.
* Added methods to get strings info from scanner device to be hosted later in
  image metadata (dpi, color mode, etc)
* Move the scan reading to a thread to get a more responcive UI.