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.