2.16 release candidate 3 imminent

[Graham Percival]

All release-Critical issues have patches which are either on a
current countdown, have been on a previous countdown, or don't
make sense to be on a countdown at all and will thus be pushed in
a few hours.

Unless any problem are found with the current countdown'ing
patches, 2.15.27 release candidate 3 will probably come out on
Monday.

There seems to be a desire to wait for 2 weeks instead of 1 week,
so that's what I'll announce?

- Graham