Documentation, consistency, bugfixes.

Breaking Changes

• Rename Cache.get_dm to Cache.get_dm_channel.
• Blocked off integrations endpoints removal (create_integration, edit_integration and sync_integration).

Bug fixes

• Proper detection and outputting of new versions available on PyPI.
• Not being able to compare applications.TeamMember with users.User
• Proper typehints in the x_emoji functions in REST.

Enhancements

• REST is now fully documented.
• Faster enum implementation which will also allow bots not to break if Discord implements new values in those enums.
• Improve HTTPResponseError to include message and code (errors.RESTErrorCode) if available for futher information on the error.