add is_open property needed by tomo v2

id11/controllers/fshutter.py

@@ -133,3 +133,5 @@ class FastShutter:
     def measure(self, open_time=1., acq_time=100e-6, delay=200e-3):
         self.calibration.measure(open_time, acq_time, delay)
 
+    def is_open(self):
+        return self.mode == "OPEN"