[Swan-commit] Changes to ref refs/heads/master

[D. Hugh Redelmeier]

New commits:
commit 063415a2a8ef5446bc43a959b31356a8d7e16504
Author: D. Hugh Redelmeier <hugh at mimosa.com>
Date:   Fri Sep 28 13:26:07 2018 -0400

    pluto: add and use in_main_thread(); make main_thread private