Mautrix

* Changed lack of media encryption dependencies (pycryptodome) to be a fatal
error like lack of normal encryption dependencies (olm) are in v0.13.0.
* Added base methods for implementing relay mode in bridges
(started by [Alejo0290] in [72]).

[Alejo0290]: https://github.com/Alejo0290
[72]: https://github.com/mautrix/python/pull/72

* Formatted all code using [black](https://github.com/psf/black)
and [isort](https://github.com/PyCQA/isort).
* Added `power_level_override` parameter to `ClientAPI.create_room`.
* Added default implementations of `delete-portal` and `unbridge` commands for bridges
* Added automatic Olm session recreation if an incoming message fails to decrypt.
* Added automatic key re-requests in bridges if the Megolm session doesn't arrive on time.
* Changed `ClientAPI.send_text` to parse the HTML to generate a plaintext body
instead of using the HTML directly when a separate plaintext body is not
provided (also affects `send_notice` and `send_emote`).
* Changed lack of encryption dependencies to be a fatal error if encryption is
enabled in bridge config.
* Fixed `StoreUpdatingAPI` not updating the local state store when using
friendly membership methods like `kick_user`.
* Switched Bridge class to use async_db (asyncpg/aiosqlite) instead of the
legacy SQLAlchemy db by default.
* Removed deprecated `ClientAPI.parse_mxid` method
(use `ClientAPI.parse_user_id` instead).
* Renamed `ClientAPI.get_room_alias` to `ClientAPI.resolve_room_alias`.

* Added wrapper for [MSC2716]'s `/batch_send` endpoint in `IntentAPI`.
* Added some Matrix request metrics (thanks to [jaller94] in [68]).
* Added utility method for adding variation selector 16 to emoji strings the
same way as Element does (using emojibase data).

[MSC2716]: https://github.com/matrix-org/matrix-spec-proposals/pull/2716
[jaller94]: https://github.com/jaller94
[68]: https://github.com/mautrix/python/pull/68

* *(util.formatter)* Added support for parsing Matrix HTML colors.

* Added autogenerated docs with Sphinx.
* Rendered version available at https://docs.mau.fi/python/latest/
(also version-specific docs at https://docs.mau.fi/python/v0.12.3/).
* Added asyncpg to client state store unit tests.
* Fixed client state store `get_members` being broken on asyncpg (broken in 0.12.2).
* Fixed `get_members_filtered` not taking the `memberships` parameter into
account in the memory store.

* Added more control over which membership states to return in client state store.
* Added some basic tests for the client state store.
* Fixed `OlmMachine.account` property not being defined before calling `load`.