add favicon, fix callback

raspberry/roberto/Serial.py

@@ -65,11 +65,11 @@ class Serial(object):
             #self.alive = False
             #raise
 
-    def add_callback(self, cmd, callback, arg=None):
+    def add_callback(self, cmd, callback, arg):
         if not cmd in self._callbacks:
             self._callbacks[cmd] = []
         self._callbacks[cmd].append( (callback, arg) )
 
-    def del_callback(self, cmd, callback, arg=None):
+    def del_callback(self, cmd, callback, arg):
         if cmd in self._callbacks:
             self._callbacks[cmd].remove( (callback, arg) )

raspberry/roberto/camera/camera_gstreamer_webrtc.py

@@ -196,7 +196,7 @@ class WebRTCCamera(Thread):
     def emit_async(self, event, data):
         self._queue.put({'job':'emit', 'event':event, 'data':data})
 
-    def send_battery(val, arg=None):
+    def send_battery(val, arg):
         print("sending battery value %s" % val)
         self.emit_async('battery', val)
 

raspberry/roberto/views/frontend/routes.py

@@ -41,3 +41,7 @@ def virtualjoystick_js():
 @frontend_blueprint.route('/manifest.json')
 def manifest_json():
     return render_template('manifest.json'), {'Content-Type': 'application/json'}
+
+@frontend_blueprint.route('/favicon.ico')
+def favicon_ico():
+    return send_file('templates/favicon.ico', mimetype='image/x-icon')