avoid deadlock in proxy

in secop.proxy the callers modules method announceUpdate is
called from an other thread while the accessLock is locked,
creating a deadlock. solve this by creating an other lock
'updateLock' for the update.

+ add status parameter even to non-Readable proxy modules,
  in order to indicate a failed connection
+ fix an error in secop_psi/softcal.py

Change-Id: Iae7c6d5a74001150a47aa9dc99209c15d972cd5e
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/28130
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop_psi/softcal.py

@@ -191,7 +191,7 @@ class Sensor(Readable):
 
     def initModule(self):
         super().initModule()
-        self._rawsensor.registerCallbacks(self, ['status'])  # auto update status
+        self.rawsensor.registerCallbacks(self, ['status'])  # auto update status
         self._calib = CalCurve(self.calib)
         if self.description == '_':
             self.description = '%r calibrated with curve %r' % (self.rawsensor, self.calib)
@@ -220,4 +220,4 @@ class Sensor(Readable):
             self.status = self.Status.ERROR, self._value_error
 
     def read_value(self):
-        return self._calib(self._rawsensor.read_value())
+        return self._calib(self.rawsensor.read_value())