Add support for specifying DNSTimeout (bumps required dkimpy version to 1.0)

man/dkimpy-milter.conf.5.in

@@ -358,6 +358,12 @@ consulting the DNS on each message.  This is useful primarily for
 testing purposes in environments where it is awkward to modify the
 system DNS resolution.  It should not be used in production.
 
+.TP
+.I DNSTimeout (integer)
+Sets the DNS timeout in seconds.  A value of 0 causes no wait (this is
+different than opendkim).  The default is 5.  See also the NOTES section
+below.
+
 .TP
 .I PeerList (dataset)
 Identifies a set of "peers" that identifies clients whose connections
@@ -511,6 +517,27 @@ unless an alternate
 .I group
 is specified.
 
+.SH NOTES
+When using DNS timeouts (see the
+.I DNSTimeout
+option above), be sure not to use a timeout that is larger than the timeout
+being used for interaction between
+.I sendmail
+and the filter.  Otherwise, the MTA could abort a message while waiting for
+a reply from the filter, which in turn is still waiting for a DNS reply.  This
+must take into accout that the timeout is per DNS lookup so the total DNS wait
+time may be subustantially loner than the value specified in
+.I DNSTimeout
+\.  There is a DNS lookup for each connection if the
+.I InternalHosts
+option is in use and one for DKIM public key record lookup for each algorithm
+per signature per message (i.e. potentially two lookups per signature).
+
+.SH FILES
+.TP
+.I @CONFDIR@/dkimpy-milter.conf
+Default location of this file.
+
 .SH "AUTHORS"
 \ddkimpy-milter\fR was written by Scott Kitterman <scott@kitterman.com>.
 It is based on dkim-milter.py  Copyright (c) 2001-2013 Business Management Systems, Inc.