galgen -- static images gallery generator

That generator is written on zsh and is aimed only to deal with JPEG XL
image format solely. JPEG XL is superior to any other format both in
lossy and lossless modes.

Just run that script inside the directory with .jxl files. For each file
the small preview will be generated in lossy WebP format. Also
corresponding HTML file is generated too, containing information about
the picture and its metadata.

You can set the following environment variables:
* PAGESIZE (100 by default)
* ORDERING ("Om" by default, zsh glob notation)
* STYLE (URL to CSS file, by default is none, no stylesheet link is set)

If it is JPEG XL, then, for compatibility reason with non-bleeding edge
software, alternative format is generated too (unless NOALT environment
variable is set): either JPEG (if JPEG XL contains losslessly transcoded
JPEG), or PNG (leaving off the alpha channel).

If image file has corresponding .txt/.html, then it will be included on
HTML page.

All images are sorted my modification date and grouped by pages, linking
them together. If directory contains ".txt"/".html", then it will be
included on the first page.

Following external utilities are called: djxl, jxlinfo, exiftool,
pamtopng, pnmscale, pngcrush, advpng, cwebp, parallel.