Add !id

The !id command returns the user ID of the current thread. Useful for
getting the user ID on mobile.

src/main.js

@@ -19,6 +19,7 @@ const greeting = require('./modules/greeting');
 const typingProxy = require('./modules/typingProxy');
 const version = require('./modules/version');
 const newthread = require('./modules/newthread');
+const idModule = require('./modules/id');
 
 const attachments = require("./data/attachments");
 const {ACCIDENTAL_THREAD_MESSAGES} = require('./data/constants');
@@ -172,6 +173,7 @@ module.exports = {
     await typingProxy(bot);
     await version(bot);
     await newthread(bot);
+    await idModule(bot);
 
     // Connect to Discord
     console.log('Connecting to Discord...');

src/modules/id.js

@@ -0,0 +1,10 @@
+const threadUtils = require("../threadUtils");
+
+module.exports = bot => {
+  const addInboxServerCommand = (...args) => threadUtils.addInboxServerCommand(bot, ...args);
+
+  addInboxServerCommand('id', async (msg, args, thread) => {
+    if (! thread) return;
+    thread.postSystemMessage(thread.user_id);
+  });
+};