API docs update

[NikoOinonen]

Fixes #264

Reorganization of the sphinx doc pages for the Python API.

• Separated all of the modules into separate pages and put them all under one category in the side-bar.
• Added the version number to the doc pages and added a bumpver pattern to automatically update it.
• Changed the theme to furo, because I thought it looks a bit nicer and it supports dark mode.
• Fixed some things which were throwing errors and warnings during the docs compilation.

A preview of the new look can be seen at https://ppafm.readthedocs.io/en/api-docs-update/.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (b0ce6d2) 46.44% compared to head (2bc55b0) 46.44%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #265 +/- ## ======================================= Coverage 46.44% 46.44% ======================================= Files 35 35 Lines 5180 5180 ======================================= Hits 2406 2406 Misses 2774 2774 ``` | [Flag](https://app.codecov.io/gh/Probe-Particle/ppafm/pull/265/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Probe-Particle) | Coverage Δ | | |---|---|---| | [python-3.10](https://app.codecov.io/gh/Probe-Particle/ppafm/pull/265/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Probe-Particle) | `46.45% <ø> (ø)` | | | [python-3.11](https://app.codecov.io/gh/Probe-Particle/ppafm/pull/265/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Probe-Particle) | `46.42% <ø> (ø)` | | | [python-3.12](https://app.codecov.io/gh/Probe-Particle/ppafm/pull/265/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Probe-Particle) | `46.42% <ø> (ø)` | | | [python-3.7](https://app.codecov.io/gh/Probe-Particle/ppafm/pull/265/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Probe-Particle) | `46.25% <ø> (ø)` | | | [python-3.9](https://app.codecov.io/gh/Probe-Particle/ppafm/pull/265/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Probe-Particle) | `46.34% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Probe-Particle#carryforward-flags-in-the-pull-request-comment) to find out more.

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[ProkopHapala]

@NikoOinonen - It is really nice you did something in this direction.

Just to understant - this whole docs is generated automatically from the comments in the code? Or is there something you add/modify manually on top of that?

[NikoOinonen]

@ProkopHapala Yes, if you follow a certain format in the code comments, then those directions like .. automodule:: ppafm.GridUtils in the .rst files will automatically generate the html pages for the corresponding modules. I put some instructions before here as well: #47.