Adding optional support for reference counting of nodes within the

DOM.  This will only be enabled if the user defines
XML_DOM_REFCOUNT_EXPERIMENTAL.  The identifiers
DOMNodeSPtr, DOMElementSPtr, and DOMAttrSPTR may be used
in any context.  Normally, these are simply typedef'd to
DOMNode *, DOMAttr *, or DOMElement * as appropriate; if XML_DOM_REFCOUNT_EXPERIMENTAL
is defined, these are typedef'd to templates that automatically enable reference counting.

Thanks to Urs Muff for making the original suggestion, and for
helping to verify this implementation.


git-svn-id: https://svn.apache.org/repos/asf/xerces/c/trunk@174944 13f79535-47bb-0310-9956-ffa450edef68