Add toJSON methods (#1859)

* tojson things

* fix client

* ignore private properties

* remove extra property descriptors

* handle primitive flattening

* remove unused import

* add toJSON to collections

* reduce stateful props

* state

* allow custom prop names when flattening

* fix client

* fix build

* fix flatten docs

* remove guild.available, cleanup permissions, remove arbitrary id reduction

* fix util import

* add valueOf as needed, update member props

* fix incorrect merge

* update permissionoverwrites and permissions

remove serialization of permissions in PermissionOverwrites#toJSON.
change Permissions#toJSON to serialize permissions, by default excluding
admin checks.

* change Permissions#toJSON to return the primitive

* Permissions#toJSON explicitly return bitfield

src/structures/Invite.js

@@ -149,6 +149,21 @@ class Invite extends Base {
   toString() {
     return this.url;
   }
+
+  toJSON() {
+    return super.toJSON({
+      url: true,
+      expiresTimestamp: true,
+      presenceCount: false,
+      memberCount: false,
+      textChannelCount: false,
+      voiceChannelCount: false,
+      uses: false,
+      channel: 'channelID',
+      inviter: 'inviterID',
+      guild: 'guildID',
+    });
+  }
 }
 
 module.exports = Invite;