Feature/traits fix (#425)

* Modify traits to remove useless inheritance (#404)

- Removes CacheAware from RestAware

* Add missing dot

* Fix code in website background

* Fix notifying new pypi versions
   - Default HEAD version to 0.0.0

* Remove guild chunker and add cache configuration (#412)

- Fix traits
   - Fix updating voice state payload
   - Remove stateless cache and stateless guild chunker
   - Clear out cache on bot close
   - Configurable cache
   - Temporarily removed guild_chunker
   - General cleanup

* Merge stateless and stateware event managers (#424)

- Remove guild chunker
  - Provide request_nonce on GuildAvailableEvent to aid users

* Address some comments in pr
  - `get_user` added in PresenceUpdateEvent
  - `MessageDeleteEvent.channel` now also asserts for None

.flake8

@@ -24,7 +24,6 @@ ignore =
 per-file-ignores =
     hikari/__init__.py:              F401,F403
     hikari/events/__init__.py:       F401,F403
-    hikari/impl/stateless_cache.py:  R102
     hikari/internal/routes.py:       FS003
     hikari/internal/time.py:         FS003
     tests/hikari/*:                  FS003,S106,D106,D104,D103,D101,D100