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/Guild.js

@@ -951,6 +951,19 @@ class Guild extends Base {
     return this.name;
   }
 
+  toJSON() {
+    const json = super.toJSON({
+      available: false,
+      createdTimestamp: true,
+      nameAcronym: true,
+      presences: false,
+      voiceStates: false,
+    });
+    json.iconURL = this.iconURL();
+    json.splashURL = this.splashURL();
+    return json;
+  }
+
   /**
    * Creates a collection of this guild's roles, sorted by their position and IDs.
    * @returns {Collection<Role>}