tl2020 pretest begin

[Karl Berry]

I think the pretest area is populated with the first build for TL 2020.
See https://tug.org/texlive/pretest.html as usual for details of how to
install (unchanged from previous years), and the list of notable changes
that I've got so far. Additions or corrections to the news are greatly
appreciated.

I have not caught up with the CTAN releases over the past few days. I
expect all of those to be updated in the pretest over the next day or two.

The binaries for a few of the platforms (cygwin, armhf-linux,
i386-netbsd) have not yet been updated. I expect that to happen soon
also.  All others are current AFAIK.

BTW, as discussed in the LaTeX newsletters and other places, lualatex in
the pretest now invokes the luahbtex engine, as lualatex-dev did for the
last couple months in TL19.

Please try it if you can. Better to test now than wait for breakage in
the official release. We have no dedicated testers or QA department, so
it's all up to us collectively as volunteers.

Hope it flies,
Karl