Breaking changes

DM Channel events do not have the channel property anymore. This differs from the previous build where this would always be None due to the deprecation of DMChannelCreate events occurring on v8.
The former also means that a standard Channel event no longer has the channel property, only a channel_id, as there is no guarantee we can have a given channel cached. Guild-related subclasses will still have this attribute.
USE_VAD permission has been renamed to USE_VOICE_ACTIVITY
role_ids now includes the ID of the @everyone role.
User.default_avatar is now called User.default_avatar_url to match User.avatar_url.
UnicodeEmoji.from_* methods are now named UnicodeEmoji.parse_*.
UnicodeEmoji.from_emoji is now named UnicodeEmoji.parse without the _emoji suffix.
CustomEmoji no longer has an app attribute, as it is now user-creatable. This attribute is still defined on KnownCustomEmoji however, as this is API generated only.

New Features

New JSON error codes are available to reference.
Member role_ids now contain the @everyone role (role with the same ID as the guild).
Emoji now has a parse method which will parse the CustomEmoji or UnicodeEmoji from the given string.
UnicodeEmoji.parse implemented.
CustomEmoji.parse implemented to parse snowflakes or valid emoji mentions.

Voice event documentation is now 50% less sarcastic than before about the broken voice endpoint attribute, as it has now been fixed to use the correct port.
...as a result, the port is now no longer hard-coded in Hikari.