Liara

* Add a `--port` option to `liara serve` to change the listen port.
* Add an `ignore_files` option to ignore certain file patterns. This is particularly useful if an editor creates lock or backup files that should be ignored.
* The file discovery process will ignore invalid index and resource files instead of failing with an exception. An error will be logged to help find the problematic files.
* Fix `liara list-content` not showing the node type on `_index` nodes.
* Handling of metadata has changed:

* Document metadata can be placed in a separate `.meta` file instead of being part of the document itself.
* Separate `.meta` files for metadata are no longer supported in the static and resource directory. This previously didn't work as expected -- resource files with `.meta` files associated had the `.meta` file processed (which would cause a failure), and static files had the `.meta` file added as a separate static file. From this release on, `.meta` files don't get any special treatment when placed in the static or resource directory trees. Static files inside the content directory continue to support metadata files.

* Mako is now installed by default, and the `mako` extra is gone. If you installed Liara using `liara[mako]`, please switch to `liara` going forward.
* `liara.template.Page.content` now returns an empty string for `IndexNode` instances. Previously, it would raise an exception.
* `liara quickstart` gained a new option, `--template-backend`, which allows selecting between jinja2 and mako templates.
* The collection sort order can be reversed now.

* Bump minimal required Python version to 3.8.
* `liara serve` now uses the cache configuration specified by the user instead of always using a filesystem cache with fixed paths.
* Add `liara.cache.RedisCache`, which uses [Redis](https://redis.io/) as the storage backend. Using Redis in a shared environment allows multiple clients to benefit from the cache. Additionally, the Redis cache allows for cache entries to expire, so it won't accumulate garbage over time (i.e. draft posts which never get published, etc.) See `configuration` for more details on how to enable Redis. Redis also requires Liara to be installed with the `[redis]` option.

* Fix `liara quickstart` not working.
* Fix a bug when fixing up timezones while using the `zoneinfo` package for timezone data.

* Deprecate `liara.template.Page.meta` in favor of `liara.template.Page.metadata` (which was newly added in this version) for consistency with `liara.template.SiteTemplateProxy.metadata`.
* Use the logger in `liara serve` instead of printing directly to the console for log messages. The default listen URL will be still printed if showing the browser is disabled.
* Set the `Content-Type` header in `liara serve`. This fixes an issue with Chrome/Edge where SVG images whould not work as they were served without a content type.
* Update `jinja2` dependency to [3.0](https://jinja.palletsprojects.com/en/3.0.x/changes/#version-3-0-0). This provides access to new Jinja2 features like required blocks.
* Update `click` dependency to [8.0](https://click.palletsprojects.com/en/8.0.x/changes/#version-8-0-0).

* Fix plugins not being packaged.