Don't include server in DM links if not needed

src/models/user.js

@@ -29,4 +29,12 @@ export default class User {
         }
         return user_id;
     }
+
+    // Get the domain out of the home_server, so if that one is e.g.
+    // "https://yourdomain.com:8008" then we return "yourdomain.com"
+    static serverDomain(home_server) {
+        const parts = home_server.split("://");
+        const serverAndPort = parts[parts.length - 1].split(/:|\//);
+        return serverAndPort[0];
+    }
 }