[lltx] luatexbase, luatextra etc.

[Manuel Pégourié-Gonnard]

Hi,

As promised, a brief summary on luatextra, luatexbase etc. Everything should
work exactly as it worked before the split, with the following packages
installed from the following branches:

- luaextra: master
- luatextra: 0.97x
- luatexbase: 0.1x

If anything doesn't work as advertised with those versions, please tell me (with
a reproducer). I'm sorry for not making "master" the compatible branch, I
realise now it makes life more complicated, I'll try not to do the same mistake
again later.

Backward-incompatible changes are present in luatexbase's master. They are
listed in at the beginning of the Changes file. We need to coordinate the
migration to luatexbase's master: everyone should check the list of incompatible
changes against his code and adapt it if necessary (or tell me if you think I
was wrong to break compatibility on this point, so we can discuss it).

The decision to migrate to luatexbase's master now or later is not mine. Please
have a look at the Changes file and tell me if you are ready to do it now and
want to delay it. If you want to do the transition now, Élie already did some
adaptations in luatextra's master. Please be aware that more incompatible
changes may be coming, but, as far as I'm concerned, I'll always keep you
informed about them.

That was for the technical part. Now for the development.

I consider mpg/luatexbase on github to be the reference version. If you want
push access to this version, it's ok with me as long as I am confident you'll
act responsibly, eg make sure you understand what the branches are for, try to
discuss before undoing things I did, and carefully check your code, before
pushing anything. I tend to prefer being bugged and fixing things myself since I
tend to think I have a fairly complete understanding of the current state of the
code and its future evolutions, so I think this way is the more effective.
However, I realise not everyone agrees, so I'll grant push access if required,
but I don't want to share push access without being sure things will be properly
discussed before (or very soon after) being acted upon.

Manuel.