Start merging post release now?

[SteveBronder]

Description

We have a pretty decent sized backlog of PRs to merge. Should we do them in some order and all the other ones have to merge after? We should get on it soon since the testing will have to sound off for each one

Current Version:

v3.1.0

[rok-cesnovar]

Lets wait for cmdstan to release (should happen soon) just to be safe and then go by number, starting with #1558 and on. Poor Jenkins will be pretty busy over the weekend :)

[rok-cesnovar]

1558, 1602, 1603, 1618, 1626, 1630, 1632, 1634 are all approved or have a comment that they are gtg after release. It might be best if someone volunteers and merges them one by one.

EDIT: Cmdstan released, we can move.

[rok-cesnovar]

Everything merged, lets close once this batch of merge-to-develop tests all pass.