[m-dev.] New release Jan 2020

[Julien Fischer]

Hi all,

As the master branch is fairly stable the moment, I intend to create a
release branch at the beginning of January, with the intention of having
being a new stable release towards the end of that month.

I'm (obviously) aware that there is a bunch of ongoing work which could
be grounds for delaying this, but (1) we *really* do need a new stable
release and (2) the only significant chunk of time I can devote to this
is in January.

Julien.