Fix: Don't serialize None on Metadata. (january embed)

Was conflicting with invite-only rauth registrations.

API: Return members when fetching messages.
Misc: Remove defunct DISABLE_REGISTRATION variable.

Permissions: Small fix, consider self as User.

Prevent removal of self / owner.

ban list.

Permissions: Use bit representation for permissions.

API: Allow removal of description on channels and servers.

Notifications: Subscribe to guild channels.

Run cargo fmt.