Add unlink clone checker. - Monitor changes of DOM-tree of the document - Unlinking a clone is actually removing the clone and copying nodes from the source. - Copy value of ID of a node to saved_id to track source of copy nodes. - For a new node with 'saved_id' is a copy of another node. - Copy vulae of 'saved_id' to 'ns0:duplicate-src' to keep the source - Change value of 'saved_id' to the value of ID of the node for later copying. - For a new node without 'saved_id' is not a copy of another node. - only set 'saved_id' to the value of its ID.

<inkscape-extension>
    <name>MadServer</name>
    <id>net.sourceforge.madbutterfly.filter.update</id>
	<dependency type="executable" location="extensions">MBServer.py</dependency>
	<dependency type="executable" location="extensions">inkex.py</dependency>
    <effect>
		<object-type>any</object-type>
		<effects-menu>
			<submenu _name="MadButterfly">
				<submenu _name="Server"/>
			</submenu>
		</effects-menu>
    </effect>
    <script>
        <command reldir="extensions" interpreter="python">MBServer.py</command>
    </script>
</inkscape-extension>