[Xerces2] DOM Update

[Andy Clark <an...@apache.org>]

I've gone ahead and implemented something in the Xerces2 concept
implementation that's been bugging me for a long time. The DOM
parser can now build attribute nodes that contain entity
references in the attribute value! :)

The design and framework for Xerces2 always had a way to keep 
track of entity reference information for attribute values but 
I hadn't written the code to support it until now.

The hard part still to come is how this entity reference info
is to be adjusted when the attribute values are normalized based
on the attribute's type.

-- 
Andy Clark * IBM, JTC - Silicon Valley * andyc@apache.org