YAML isn't part of the Python standard library, while JSON is.
If we want `setup.py` to dynamically parse the available integration
manifest files in order to populate the extra dependencies, then it's
better to rely on a JSON format for manifest files - the parser is part
of the standard library and it doesn't require the user to install
`pyyaml` before `platypush`.
Added an `add_dependencies` plugin to the Sphinx build process that
parses the manifest files of the scanned backends and plugins and
automatically generates the documentation for the required dependencies
and triggered events.
This means that those dependencies are no longer required to be listed
in the docstring of the class itself.
Also in this commit:
- Black/LINT for some integrations that hadn't been touched in a long
time.
- Deleted some leftovers from previous refactors (deprecated
`backend.mqtt`, `backend.zwave.mqtt`, `backend.http.request.rss`).
- Deleted deprecated `inotify` backend - replaced by `file.monitor` (see
#289).
- Provide relevant examples for schema fields with no description/examples based on the field type
- Fixed RST warnings in Slack plugin
- Fixed list of events in ngrok plugin
