lighttpd mkdocs plugin

Used to build various mkdocs sites, based on:

• mkdocs-material (plugin collection)
• mkdocs 1.6 (unlikely to work with >=2.0)

Load with:

plugins:
  - lighttpd
  ...

Currently the only thing it does is extending the materials blog plugin.

blog extension

Based on https://squidfunk.github.io/mkdocs-material/plugins/blog/.

The blog plugin removes the blog pages from the main files collection, and adds them back as Posts (a subclass of Page). It then tries to parse the metadata of the post, requiring a date. It doesn't allow the normal plugin system to fill in date; it only allows the material/meta plugin to add metadata from .meta.yml files.

Given we don't use material/meta, this plugin injects a plugin with the same name (yes, an ugly hack), and can then derive the date (and slug) from the post filename (YYYY-MM-DD-slug.md).

We also derive categories from the path components under the post_dir.

All derived meta fields can be overwritten in the post.