Implement LaTeX footnotes using `\footnotemark` and `\footnotetext` (#32

)

* use \footnotetext and \footnotemark to implement LaTeX footnotes

* git diff be62b2b c3be50e > src/patches/latex-footnotes.diff

* add tests, news, and bump version

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Co-authored-by: Jeroen Ooms <jeroenooms@gmail.com>

Fix version

Fix -Wstrict-prototypes

Add a link

Suggest xml2 for tests

Wording

Bump

Update example

Prepare for release

Update readme