gh-36861: Use lualatex for better unicode support
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to support https://github.com/sagemath/sage/pull/36857.
There have been numerous problems due to limited support of unicode in
pdflatex. I see no reason why we should not switch to modern tex engine
lualatex, as suggested in
https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-
latex_engine
We set lualatex as the default engine for
- building the sage documentation, in `sage_docbuild/`
- rendering pdf images, in `src/sage/misc/latex.py`
In `src/sage/misc/latex.py`, the default engine is determined by
availability of the engines with the order of preference: lualatex,
xelatex, pdflatex.
Along the way, we
- remove latex-related code deprecated in #32650.
- make lots of cosmetic edits in `src/sage/misc/latex.py`
- add support "lualatex" as an alternative to "[pdf|xe]latex" in
`src/sage/misc/latex.py`
We add optional (dummy) packages `texlive_luatex`, `free_fonts`, `xindy`
as new dependencies of `sagemath_doc_pdf` in addition to `texlive`
optional package. It seems that depending on the version and the
platform, `texlive` may already include the new dependencies. If not,
you need to install the new dependencies (as `_recommended` by the dummy
package)
On Ubuntu, the requirement is fulfilled by
```
sudo apt install texlive texlive-luatex fonts-freefont-otf xindy
```
The built pdf doc is available here: https://deploy-livedoc--
sagemath.netlify.app
To test `view` via lualatex, for example,
```
latex.extra_preamble(r"\usepackage{fontspec}\setmainfont{Arial}\setmonof
ont{Arial}")
view('Εύρηκα')
```
you should build sage on your local platform with this PR. You may need
to install `texlive-full` before testing. It seems that `texlive` (2019)
is not enough even for the `view` via pdftex.
sage-devel thread seeking Unicode testers:
https://groups.google.com/g/sage-devel/c/tG2LK6Jvw0I
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Resolves #18370
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### :hourglass: Dependencies
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URL: https://github.com/sagemath/sage/pull/36861
Reported by: Kwankyu Lee
Reviewer(s): Dima Pasechnik, Kwankyu Lee, Matthias Köppe
