feat: Update

- Event for GroupDM
- Friend nickname
#29

src/client/websocket/handlers/RELATIONSHIP_UPDATE.js

@@ -0,0 +1,18 @@
+'use strict';
+
+const { Events, RelationshipTypes } = require('../../../util/Constants');
+
+module.exports = (client, { d: data }) => {
+  client.relationships.cache.set(data.id, data.type);
+  /**
+   * Emitted whenever a relationship is updated.
+   * @event Client#relationshipUpdate
+   * @param {Snowflake} user The userID that was updated
+   * @param {RelationshipTypes} type The new relationship type
+   * @param {Object} data The raw data
+   */
+  if ('nickname' in data) {
+    client.user.friendNicknames.set(data.id, data.nickname);
+  }
+  client.emit(Events.RELATIONSHIP_UPDATE, data.id, RelationshipTypes[data.type], data);
+};