Update for new information on PQsetNoticeProcessor().

Now back in sync with libpq.3 man page, which should be obsolete soon.

doc/src/sgml/libpq.sgml

@@ -129,8 +129,8 @@ sets the default cost for indexed searches for the optimizer.
 </Para>
 
 <Para>
-See the set(l)
-man page for information on the arguments for these environment variables.
+Refer to the <command>SET</command> <acronym>SQL</acronym> command
+for information on the arguments for these environment variables.
 
 </Sect1>
 
@@ -1073,6 +1073,49 @@ void PQuntrace(PGconn *conn)
 
 </Sect1>
 
+<Sect1>
+<Title>
+<FileName>libpq</FileName> Control Functions</Title>
+
+<Para>
+<ItemizedList>
+<ListItem>
+<Para>
+<Function>PQsetNoticeProcessor</Function>
+Control reporting of notice and warning messages generated by libpq.
+<ProgramListing>
+void PQsetNoticeProcessor (PGconn * conn,
+        void (*noticeProcessor) (void * arg, const char * message),
+        void * arg)
+</ProgramListing>
+</Para>
+</ListItem>
+</ItemizedList>
+</Para>
+
+<Para>
+By default, <filename>libpq</filename> prints "notice" messages from the backend on stderr,
+as well as a few error messages that it generates by itself.
+This behavior can be overridden by supplying a callback function that
+does something else with the messages.  The callback function is passed
+the text of the error message (which includes a trailing newline), plus
+a void pointer that is the same one passed to <function>PQsetNoticeProcessor</function>.
+(This pointer can be used to access application-specific state if needed.)
+The default notice processor is simply
+<ProgramListing>
+static void
+defaultNoticeProcessor(void * arg, const char * message)
+{
+    fprintf(stderr, "%s", message);
+}
+</ProgramListing>
+
+<Para>
+To use a special notice processor, call <function>PQsetNoticeProcessor</function> just after
+any creation of a new PGconn object.
+
+</Sect1>
+
 <Sect1>
 <Title>User Authentication Functions</Title>
 
@@ -1124,7 +1167,7 @@ void fe_setauthsvc(char *name,
 </Sect1>
 
 <Sect1>
-<Title>BUGS</Title>
+<Title>Caveats</Title>
 
 <Para>
      The  query  buffer is 8192 bytes long, and queries over