Allow for DOM node variables to be streamed out in t:insert

[mpo]

In r1564 we introduced the ability to insert the XML captured in a template-variable.

However this new feature will not work with variables holding DOM tree nodes (docs, fragments, elements, text nodes...) in stead of their string representation.

Using an 'no-transformation' transformerhandler from javax.xml.tranform. it should be possible to convert the dom-node into a stream of sax-events used in the template-engine.