Move the more commonly used filter to the left and the less
commonly used "purge unused sites" button to the right. Add
a spacer so that the filter-textbox doesn't extend over the
whole free space.
With apologies to sinistroverse users (is there an option to
make the layout direction depend on the locale?).
Suggested-by: Hartley Horwitz <hhrwtz@gmail.com>
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>