Instructions for building Ubuntu packages

Signed-off-by: Miika Turkia <miika.turkia@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Use getSaveFileName() as the file open dialog

This way we can specify file names that don't exist and therefore make our
git syntax (/path/to/dir[branch]) work.

Thanks to Tomaz for pointing this out.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>