Revert "coredevice: automatically close on pause"

This reverts commit 1f50b3428e.

RELEASE_NOTES.rst

@@ -30,8 +30,6 @@ 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.
 * The result folders are formatted "%Y-%m-%d/%H instead of "%Y-%m-%d/%H-%M".
   (i.e. grouping by day and then by hour, instead of by day and then by minute)
 * GUI tools save their state file in the user's home directory instead of the

artiq/coredevice/comm_generic.py

@@ -92,10 +92,6 @@ class CommGeneric:
         The channel is assumed to be opened."""
         raise NotImplementedError
 
-
-    def pause(self):
-        self.close()
-
     #
     # Reader interface
     #