SVGs do not honor the "Transparent background" config option, and simply have no
background at all. This patch ensures this option is applied to SVGs as well as
Unlike RasterImageView that uses a QPixmap buffer (mCurrentBuffer) for drawing
the background and the image, SVGs are rendered directly on top of SvgImageView
(QGraphicsWidget). Therefore we just paint the background in SvgImageView::paint
which happens before the SVG is rendered.
We move the checkboard texture code to AbstractImageView now that it's used by
both subclasses RasterImageView and SvgImageView.
This patch also configures kconf_update due to the moving of the above enum.
Since I didn't want to litter /app with files, I've moved the update files to