[api] Add connected property to RemoteControl

Author: ddemidov

ev3dev/core.py

@@ -1879,6 +1879,10 @@ def __init__(self, sensor=None, channel=1):
         if self._sensor.connected:
             self._sensor.mode = 'IR-REMOTE'
 
+    @property
+    def connected(self):
+        return self._sensor.connected
+
     @property
     def buttons_pressed(self):
         """