[Qgis-psc] 2.18.9 - big thanks to Jürgen for the quick release!

[Nyall Dawson]

I'd really like to publicly extend my thanks to Jürgen for this prompt
release of 2.18.9, and for the work he's put in to quickly backport
fixes and squash critical bugs leading up to this.

This makes the second point release in a row where Jürgen has been
required to push out rapid follow up releases, through no fault of his
own!

Jürgen -- without your hard work as release manager and all the hours
you put in to packaging QGIS releases there's no way we'd have
achieved the success we enjoy today. Many many thanks for all the work
you've put in over the years in this thankless task!

Nyall