remove old chat messages

raspberry/roberto/views/frontend/templates/index.html

@@ -200,6 +200,9 @@ socket.on('text', (data) => {
   var new_message = document.createElement('p');
   new_message.innerHTML = data.data;
   chatlog.append(new_message);
+  if (chatlog.children.length > 10) {
+    chatlog.children[0].remove();
+  }
 });
 
 function displayText(text, left, top) {