Start using the message plugin

This is instead of using the stanza directly. To get this to work,
we had to import a couple of other util libraries just so that
they assign their respective utils to Converse's `u` object. This
is probably supposed to happen by itself when the respective
plugins are loaded, but for whatever reason it wasn't happening so
here we are.

src/converse.js

@@ -17,11 +17,21 @@ import "@converse/headless/plugins/smacks/index.js";     // XEP-0198 Stream Mana
 import "@converse/headless/plugins/status/index.js";
 import "@converse/headless/plugins/vcard/index.js";      // XEP-0054 VCard-temp
 
+// We're just importing these to activate the addon
 import {
     convertASCII2Emoji,
     getShortnameReferences,
     getCodePointReferences
 } from '@converse/headless/plugins/emoji/utils.js';
+import {
+    appendArrayBuffer,
+    arrayBufferToBase64,
+    arrayBufferToHex,
+    arrayBufferToString,
+    base64ToArrayBuffer,
+    hexToArrayBuffer,
+    stringToArrayBuffer
+} from '@converse/headless/utils/arraybuffer.js';
 
 
 window.converse = converse;
@@ -52,12 +62,10 @@ converse.plugins.add('convo', {
     })
 
     _converse.api.listen.on('connected', () => {
-      console.debug("Presence, let's go ;)")
-      _converse.api.send(converse.env.$pres({}))
-      alert("Connected! Unfortunately the next screen isn't ready so we'll just wait here :P")
+      console.debug('Connected successfully ;)')
 
       _converse.api.listen.on('message', (msg) => {
-        alert(`${msg.attrs.from} says: ${msg.attrs.body}`)
+        console.debug(`${msg.attrs.from} says: ${msg.attrs.body}`)
       })
     })