Multiple version of Lua with alternatives

[Lemures Lemniscati]

Hi!

Helped by advices from Achim [1],
I prepared an experimental tree for Lua [2], as a first step.
And I'd like to request for comments about it.

* lua is forked into lua54 and lua53. It is also obsoleted by lua53.
  we can select versions by alternatives

* A new source luarocks provides lua53- and lua54-luarocks.
  They install rocks into an alternative tree /var/lib/lua-site/.

* Sources lua-crypto, lua-json, lua-ldap, lua-lfs, lua-lgi, lua-logging,
  lua-lpeg, and lua-lxp now provide lua{53,54}-* packages.

* New sources lua-ldoc, lua-luaossl, lua-lunitx, and, lua-plprovide
lua{53,54}-* packages.

* lua-luadoc is very old and obsoleted, so it is not updated.


[1]: https://sourceware.org/pipermail/cygwin-apps/2021-January/040983.html
[2]: https://cygwin-lem.github.io/lua-cygwin-packages/

Regards,
Lem