GitLab

CI config now dry as a desert, with everything based around the (also improvided) Makefile(s)

This flushes all PDFs fetched from the cache

Caching can be an important performance boost.
With no caching, LaTeX has to regenerate all auxiliary files,
including glossary and bib files, every time.
This also applies to SVG files that were automatically
converted to PDF using the svg package (with inkscape
in the background). Discarding these PDFs each time is also
costly.

Existing auxiliary files help latexmk finish in fewer runs.

In a first attempt, caching reduced pipeline run times by 50%.

Also just CI config accordingly

More debug output, and better/more suitable latexmkrc file

Removes redundancy, clears the script up a lot

For visibility

Tries to fix container not found error, saving a manual retry

Eisvogel template is now in the Docker image; new Docker image also fixes 'svg'

Also rework sed lines a bit