coredevice: automatically close on pause

RELEASE_NOTES.rst

@@ -30,6 +30,8 @@ unreleased [2.x]
 
   (you may need to replace python3.5 with python)
   Please always include the console output when reporting a GUI crash.
+* Closing the core device communications before pausing is done automatically.
+  Experiments no longer need to do it explicitly.
 
 
 unreleased [1.0rc3]

artiq/coredevice/comm_generic.py

@@ -87,6 +87,10 @@ class CommGeneric:
         The channel is assumed to be opened."""
         raise NotImplementedError
 
+
+    def pause(self):
+        self.close()
+
     #
     # Reader interface
     #