ximea: define handle attribute during __init__()

Author: NickHallPhysics

microscope/cameras/ximea.py

@@ -49,6 +49,7 @@ def __init__(self, *args, **kwargs):
         self._acquiring = False
         self._exposure_time = 0.1
         self._triggered = False
+        self.handle = None
 
     def _purge_buffers(self):
         """Purge buffers on both camera and PC."""