* Using -m X (X standing for screen number) the give background image is
converted to a big image in the <cache directory>/montage.png.
Limitations:
+ -m should be the last argument before the image name
+ for better results screens should have the same sizes and the background
image should fit one screen size.
Signed-off-by: Sébastien Gross <seb-awesome@chezwam.org>
Signed-off-by: Julien Danjou <julien@danjou.info>