Add support for mock vehicle

control/gpiozero/mockvehicle.py

@@ -0,0 +1,42 @@
+
+
+# A dummy vehicle class to use when 
+class MockVehicle:
+    def __init__(self, motor_pin=19, servo_pin=18):
+        self.motor_pin = motor_pin
+        self.steering_pin = servo_pin
+
+    @property
+    def throttle(self):
+        return self._throttle
+
+    @throttle.setter
+    def throttle(self, value):
+        self._throttle = value
+
+    @property
+    def steering(self):
+        return self._steering
+
+    @steering.setter
+    def steering(self, value):
+        self._steering = value
+
+    @property
+    def motor_pin(self):
+        return self._motor_pin
+
+    @motor_pin.setter
+    def motor_pin(self, value):
+        self._motor_pin = value
+
+    @property
+    def steering_pin(self):
+        return self._steering_pin
+
+    @steering_pin.setter
+    def steering_pin(self, value):
+        self._steering_pin = value
+
+    def stop(self):
+        self.throttle = 0