SciPDL as Homebrew formula, possibly also GitHub releases

We ought to have a Homebrew formula for PDL, then for a SciPDL that includes that. Instructions on how: https://docs.brew.sh/Formula-Cookbook

#367 mentions https://www.mail-archive.com/pdl-porters@jach.hawaii.edu/msg05839/scipdl-2.007-maverick.pod for SciPDL 2.007 (by @mkenworthy) with detailed build instructions for that. It includes:

• http://search.cpan.org/CPAN/authors/id/K/KG/KGB/ExtUtils-F77-1.17.tar.gz
• http://search.cpan.org/CPAN/authors/id/K/KG/KGB/PGPLOT-2.20.tar.gz
• http://search.cpan.org/CPAN/authors/id/D/DC/DCONWAY/Parse-RecDescent-1.962.2.tar.gz
• http://search.cpan.org/CPAN/authors/id/S/SI/SISYPHUS/Inline-0.45.tar.gz
• http://search.cpan.org/CPAN/authors/id/D/DC/DCONWAY/Parse-RecDescent-1.96.0.tar.gz
• http://search.cpan.org/CPAN/authors/id/J/JP/JPEACOCK/version-0.78.tar.gz
• http://www.promotionalpromos.com/mirrors/gnu/gnu/gsl/gsl-1.13.tar.gz
• http://www.fftw.org/fftw-2.1.6.tar.gz
• http://search.cpan.org/CPAN/authors/id/T/TJ/TJENNESS/Astro-FITS-Header-3.01.tar.gz
• http://search.cpan.org/CPAN/authors/id/P/PR/PRATZLAFF/Astro-FITS-CFITSIO-1.05.tar.gz
• http://search.cpan.org/CPAN/authors/id/C/CH/CHM/OpenGL

https://sourceforge.net/projects/pdl/files/SciPDL/ lists what's included for SciPDL 2.017 (by @karlglazebrook):

• XQuartz (actually you need to download it)
• its Perl deps
• ExtUtils::F77 1.19
• Astro::FITS::Header 3.07
• Astro::FITS::CFITSIO 1.10
• PGPLOT 2.21
• PDL::FFTW3 0.04
• Term::ReadLine::Gnu 1.25
• pgplot 5.3.1 (see https://github.com/djerius/pgplot-autotool/issues/1 for getting this, and licensing and maybe using Giza instead)
• libpng 1.2.8
• zlib 1.2.3
• fftw 3.3.4
• cfitsio 3.370
• gsl 1.16
• readline 5.1

Also recently (at the time of writing) a SciPDL 2.025 as a GitHub "release" by @karlglazebrook visible at https://github.com/PDLPorters/pdl/releases/tag/untagged-1ff8920233b6f6ee9c33, with assets (mostly from the README.pdf):

• libquadmath plus instructions to install
• instructions to use MacPorts xorg
• Perl 5.32
• PDL 2.025
• Astro-FITS-CFITSIO-1.15
• ExtUtils-F77-1.20
• PDL-FFTW3-0.06
• cfitsio-3.49
• fftw-3.3.9
• gsl-v2.6
• libpng-1.6.37
• perl5-PGPLOT-2.24
• libpgplot5.3.1

Also we might automate creating at least a draft release for each tag, see https://github.com/PDLPorters/pdl/releases for ones created by the mighty @d-lamb up to 2.026.

Start with the Homebrew Formula Cookbook and issue #367, then compare the SciPDL 2.017 and 2.025 dependency lists with the existing releases page. Determine whether the scope is a Homebrew formula, draft releases for tags, or both; done should include a documented, reproducible packaging or release process.