nodes now are much smaller.
The main changes are:
renamed NodeContainer to ParentNode,
introduced ChildNode and ChildAndParentNode,
all the boolean attributes have been changed to bit flags,
ownerDocument is no longer an attribute of NodeImpl, only Parent nodes have
it, leave nodes rely on their parent to get it, or get it from ownerNode when
they do not have a parent,
parent Nodes no longer have a direct pointer to the last child
instead the last child is stored as the previous sibling of
the first child.
I also added support for importing a DocumentType as it's done in Java,
and got the importNode mechanism back in sync with Java as well.

Here are the most significant changes in size:
ElementImpl 52 -> 48
TextImpl    44 -> 32
AttrImpl    52 -> 36


git-svn-id: https://svn.apache.org/repos/asf/xerces/c/trunk@172078 13f79535-47bb-0310-9956-ffa450edef68