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/GuildAuditLogs.js

@@ -1,6 +1,7 @@
 const Collection = require('../util/Collection');
 const Snowflake = require('../util/Snowflake');
 const Webhook = require('./Webhook');
+const Util = require('../util/Util');
 
 /**
  * The target type of an entry, e.g. `GUILD`. Here are the available types:
@@ -220,6 +221,10 @@ class GuildAuditLogs {
 
     return 'ALL';
   }
+
+  toJSON() {
+    return Util.flatten(this);
+  }
 }
 
 /**
@@ -371,6 +376,10 @@ class GuildAuditLogsEntry {
   get createdAt() {
     return new Date(this.createdTimestamp);
   }
+
+  toJSON() {
+    return Util.flatten(this, { createdTimestamp: true });
+  }
 }
 
 GuildAuditLogs.Actions = Actions;