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/util/Util.js

@@ -395,7 +395,7 @@ class Util {
       .replace(/@(everyone|here)/g, '@\u200b$1')
       .replace(/<@!?[0-9]+>/g, input => {
         const id = input.replace(/<|!|>|@/g, '');
-        if (message.channel.type === 'dm' || message.channel.type === 'group') {
+        if (message.channel.type === 'dm') {
           const user = message.client.users.get(id);
           return user ? `@${user.username}` : input;
         }
@@ -413,7 +413,7 @@ class Util {
         return channel ? `#${channel.name}` : input;
       })
       .replace(/<@&[0-9]+>/g, input => {
-        if (message.channel.type === 'dm' || message.channel.type === 'group') return input;
+        if (message.channel.type === 'dm') return input;
         const role = message.guild.roles.get(input.replace(/<|@|>|&/g, ''));
         return role ? `@${role.name}` : input;
       });