Alllow arbitrary folder as output directory of docbuild

[tobiasdiez]

It was not possible to specify an arbitrary folder as the output of the docbuild, because the citation extension had an assertion that checked that the output directory was a subfolder of SAGE_DOC. This check is replaced by providing some default folder for the citations in case the output directory is not below SAGE_DOC.

This is allows to build the documentation by running sphinx manually, which is required by some tools (e.g. the restructuredtext extension for VS code provides a HTML preview of the currently edited rst file by running sphinx on it).

I also used the opportunity to convert the code in question to use pathlib.

CC: @tscrim @nthiery @fchapoton @mkoeppe @jhpalmieri

Component: documentation

Author: Tobias Diez

Branch: ad75421

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/31221

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

[sagetrac-git]

Commit: 9d686f2

[sagetrac-git]

Changed commit from 9d686f2 to ad75421

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

ad75421

Alllow arbitrary folder as output directory of docbuild

[mkoeppe]

comment:5

Patchbot is green, looks fine to me.

[mkoeppe]

Reviewer: Matthias Koeppe

[tobiasdiez]

comment:6

Thanks!

[vbraun]

Changed branch from public/documentation/allow-from-arbitrary-folder to ad75421

[fchapoton]

Changed commit from ad75421 to none