Partials (#3070)

* Remove GroupDMChannels

they sparked no joy

* Start partials for message deletion

* MessageUpdate partials

* Add partials as an opt-in client option

* Add fetch() to Message

* Message.author should never be undefined

* Fix channels being the wrong type

* Allow fetching channels

* Refactor and add reaction add partials

* Reaction remove partials

* Check for emoji first

* fix message fetching

janky

* User partials in audit logs

* refactor overwrite code

* guild member partials

* partials as a whitelist

* document GuildMember#fetch

* fix: check whether a structure is a partial, not whether cache is true

* typings: Updated for latest commit (#3075)

* partials: fix messageUpdate behaviour (now "old" message can be partial)

* partials: add warnings and docs

* partials: add partials to index.yml

* partials: tighten "partial" definitions

* partials: fix embed-only messages counting as partials

src/client/actions/MessageUpdate.js

@@ -4,11 +4,10 @@ const Action = require('./Action');
 
 class MessageUpdateAction extends Action {
   handle(data) {
-    const client = this.client;
-
-    const channel = client.channels.get(data.channel_id);
+    const channel = this.getChannel(data);
     if (channel) {
-      const message = channel.messages.get(data.id);
+      const { id, channel_id, guild_id, author, timestamp, type } = data;
+      const message = this.getMessage({ id, channel_id, guild_id, author, timestamp, type }, channel);
       if (message) {
         message.patch(data);
         return {