Re: proposal - psql - use pager for \watch command

Here's a rebase, due to a conflict with 3a513067 "psql: Show all query
results by default" which moved a few things around making it harder
to use the pager for the right scope.  Lacking time, I came up with
this change to PSQLexecWatch():

+       if (printQueryFout)
+       {
+               restoreQueryFout = pset.queryFout;
+               pset.queryFout = printQueryFout;
+       }
+
        SetCancelConn(pset.db);
        res = SendQueryAndProcessResults(query, &elapsed_msec, true);
        ResetCancelConn();

        fflush(pset.queryFout);

+       if (restoreQueryFout)
+               pset.queryFout = restoreQueryFout;
+

If someone has a tidier way to factor this, I'm keen to hear it.  I'd
like to push this today.