Pg: Add text2bin() and bin2text() conversion methods

FU/Pg.pm

@@ -780,9 +780,24 @@ to be sent to (and further validated by) Postgres.  For some types,
 C<perl2bin()> may return invalid data on invalid input and C<bin2perl()> may
 accept invalid binary data.
 
-=back
+=item $conn->bin2text($oid, $bin, ...)
 
-I<TODO:> Methods to convert between bin and text formats.
+=item $conn->text2bin($oid, $text, ...)
+
+Convert between the binary format and the PostgreSQL text format. This
+conversion requires a round-trip to the server and throws an error if the
+connection state is not I<idle> or I<txn_idle>. Since it is Postgres doing the
+conversion, the input is properly validated and, in the case of C<bin2text()>,
+the result is guaranteed to be suitable for use as a textual bind parameter or
+for inclusion in an SQL query (but don't forget to use C<escape_literal()> in
+that case).
+
+Calling these methods many times can be pretty slow. If you have several values
+to convert, you can do that in a single call to speed things up:
+
+  my($text1, $text2, ..) = $conn->bin2text($oid1, $bin1, $oid2, $bin2, ..);
+
+=back
 
 I<TODO:> Methods to query type info.