Add 2 icons for filter and sort capabilities. And as before, these
icons are coming from the Google Material design set.
[Dirk Hohndel: Jan's commit forgot to add the actual icons, I added
those so the commit matched its message]
Signed-off-by: Jan Mulder <jlmulder@xs4all.nl>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
