crudexml -- Crude XML DOM module

Simple and crude write-only XML DOM implementation.
It does not read XML data, only produces XML text from the node objects provided here.
Attributes are supported; namespaces are not.
Finally, it is possible to get a "pretty" output using the OuterXMLPretty getter property.

_node is a base class with most of the functionality, with node being the "general" node type and tnode for text nodes.
The intent is that these nodes have either node children or one tnode child.
This keeps things simpler.
Also, unlike Real DOM Implementations, the text node is a named node with text underneath it.

Example use:

	from crudexml import node, tnode

	root = node('dvd', numtitles=7, parser="pydvdread %s"%1.0)
	root.AddChild( tnode('device', "/dev/sr0") )
	root.AddChild( tnode('name', "BLOOD_DIAMOND", fancy="Blood Diamond") )
	root.AddChild( tnode('vmg_id', "DVDVIDEO-VMG") )
	root.AddChild( tnode('provider_id', "WARNER_HOME_VIDEO") )
	titles = root.AddChild( node('titles') )

Attributes are passed as named keywords to node() and tnode(), and can be accessed by using [...] on node nbjects.
node.AddChild() returns the supplied node as with @titles above.
The OuterXMLPretty for the above produces:

	<?xml version="1.0" ?>
	<dvd numtitles="7" parser="pydvdread 1.0">
		<device>/dev/sr0</device>
		<name fancy="Blood Diamond">BLOOD_DIAMOND</name>
		<vmg_id>DVDVIDEO-VMG</vmg_id>
		<provider_id>WARNER_HOME_VIDEO</provider_id>
		<titles/>
	</dvd>

Additionally, the DOCTYPE is supported.

	from crudexml import node, tnode, dnode, docroot

	d = docroot()
	d.AddChild( dnode('foo', 'bar.dtd') )

	root = d.AddChild( node('dvd', numtitles=7, parser="pydvdread %s"%1.0) )
	root.AddChild( tnode('device', "/dev/sr0") )
	root.AddChild( tnode('name', "BLOOD_DIAMOND", fancy="Blood Diamond") )
	root.AddChild( tnode('vmg_id', "DVDVIDEO-VMG") )
	root.AddChild( tnode('provider_id', "WARNER_HOME_VIDEO") )
	titles = root.AddChild( node('titles') )

And the XML:

	<?xml version="1.0" ?>
	<!DOCTYPE foo
	  SYSTEM 'bar.dtd'>
	<dvd numtitles="7" parser="pydvdread 1.0">
		<device>/dev/sr0</device>
		<name fancy="Blood Diamond">BLOOD_DIAMOND</name>
		<vmg_id>DVDVIDEO-VMG</vmg_id>
		<provider_id>WARNER_HOME_VIDEO</provider_id>
		<titles/>
	</dvd>

The docroot() produces no XML for itself (i.e., OuterXML == InnerXML) and why the DOCTYPE and <dvd>...</dvd> are shown at the "root" level.

