Add support for XInclude when parsing XML

XInclude allows to external content to be included while parsing a XML document.

We have to include XML into other XML files in multiple szenarios:

• rules.xml of fact-based access system

• XEditor

• …

Is there a chance to bring up a unified solution for all this use cases by supported the XInclude-Standard.

Warning!
There may be security issues, because it could be possible to include any xml file from the resource path - including files with confidential information.

This becomes relevant if end users (e.g. via WEB-CLI) kann modify XML files directly and so add <xinclude> elements which then can output this confidential information.