Many things pushed out to 'master'

I've merged a handful topics that have been cooking in 'next' to
'master'.  Except for a few big topics still in 'next', this brings the
tip of 'master' much closer to what will become 1.5.4.

As always has been promised, the tip of 'master' is designed to be more
stable than any released version without introducing regression, and we
need to test how true that is from time to time ;-).

Please keep the fixes flowing.  The next batch will be "commit in C" and
"add --patch" series.