Bug 7257: xmpp: added support for xml element in a body of a message

xmpp-bot: added support for xml element in a body of a message

web-framework:
* implemented print-change generic function (which returns a string)
* added support for a base-url keyword to send uris, not only relative links
  (in print-change and print-xml)
* export valid-user? GF

buddha:
 * hardcoded ns.ripe.net as authoritative NS for ipv4 reverse delegations
 * fix printing of dhcpd config file 
 * use xmpp bot for changes
 * use http authentication instead of cookies and http forms

library.dylan

@@ -7,7 +7,7 @@ define library xmpp-bot
   use io;
   use system;
   use xmpp;
-  use xml-parser, import: { simple-xml };
+  use xml-parser, import: { simple-xml, xml-parser };
 
   // Add any more module exports here.
   export xmpp-bot;

module.dylan

@@ -10,6 +10,7 @@ define module xmpp-bot
   use standard-io;
   use xmpp;
   use simple-xml;
+  use xml-parser;
 
   // Add binding exports here.
   export <xmpp-bot>, broadcast-message;

xmpp-bot.dylan

@@ -84,7 +84,7 @@ define method auto-subscriber (xmpp-bot, client, presence)
   end;
 end;
 
-define method broadcast-message (bot :: <xmpp-bot>, message :: <string>)
+define method broadcast-message (bot :: <xmpp-bot>, message :: type-union(<string>, <element>))
   do(method (user)
        send(bot.client,
             make(<message>,