[ui] Reconstruction: Restore the Slot status of the clear method

Author: cbentejac

meshroom/ui/reconstruction.py

@@ -518,6 +518,7 @@ def __del__(self):
     def setActive(self, active):
         self._active = active
 
+    @Slot()
     def clear(self):
         self.clearActiveNodes()
         super().clear()