ENH: Add XdmfHDF5Controller so that heavy data can be written and released before light data is written.
Modify XdmfWriter to accept an XdmfHDF5Writer to use for heavy data writing and allow users to specify
XML file name to write to.  Add a test that performs the write release write release workflow.

was structured when the dataset was written and we want to fully separate dealing with light and heavy
data when creating Xdmf files.  This will allow us to move towards complete separation of
heavy and light data writing, a Create -> Write -> Release -> Create -> Write -> Release -> Write XML
workflow.

ENH: Add tests using new XdmfHDF5Writer exclusively.  Modify some methods in XdmfHDF5Writer to get everything working as expected.

ENH: Remove getHDF5Type from XdmfArray and move into XdmfHDF5Writer so all hdf5 interaction is isolated
in XdmfHDF5Writer.  Friend the XdmfHDF5Writer from XdmfArray so that it can access the variant to perform
typesafe operations on the data stored.  Variable macro generation didn't work so reverted the modified code.
We may just have to write ugly static New() methods when required.

ENH: Split heavy data writing from XdmfWriter into XdmfHDF5Writer.  This paves the way for the possiblity of having multiple
heavy data and light data writers.  Modify New() macro to accept parameters.

to write out the Xdmf graph.  Modify some random include statements for style.

ENH: Add pure virtual getItemTag method to XdmfItem working to return the tag (same as in XML terminology) for the specific item.

ENH: Add XdmfItemProperty to genericize properties attached to XdmfItems.  Add a pure virtual getItemProperties() method
to XdmfItem to force children to implement a way to retrieve properties.

ENH: Create a generic XdmfVisitor class and move writing operations to XdmfWriter.  Incorporate Loki library to perform asymmetric visitor operation (allows customizable behavior for eventual Xdmf / NetDMF library split).  Modify Loki
Visitor to work happily with boost::shared_ptr and modify swig wrapping to properly handle boost::shared_ptr inheritance.

ENH: Rename write() operation to accept() which is more consistent for the Visitor pattern.  Also, we can
do much more to our Xdmf graph structure than just write it using Visitor operations.

ENH: Add transferOwnership parameter to setValues(std::vector<T> & array) to match other setValues(const T * const array) --- clarification of ownership for non-shared_ptr arrays.

ENH: Add ArrayPointer Variant to allow users to use XdmfArray merely as a "pointer holder" for output using Xdmf.  See the docs for a more clear explanation.  Modify XdmfArray methods to correctly use the ArrayPointer.

ENH: Add TestXdmfVisitorValueCounter to demonstrate how to write visitor operations over the Xdmf graph that do something other than write to disk.  Separate hexahedron grid example into a header file so that other test cases can use it for testing.

ENH: Remove XdmfPython.cpp and Xdmf.py from repository.  Modify CMake build script to generate wrappers automagically with swig (this will ensure that users always have swig wrapper tailored to their version of python and prevents us from having to regenerate and commit every time something in Xdmf changes).  Add a couple extra methods to XdmfArray.cpp --- still need to figure out the rest of XdmfArray functionality.

ENH: Add initialize() method that allows user to specify the type of data to store in an XdmfArray if desired.

ENH: Add swap method to XdmfArray.  Swap works by swapping an XdmfArray's contents internally (no copy) between a std::vector<T>, boost::shared_ptr<std::vector<T> > or another XdmfArray.  Modify some methods in XdmfArray that did not require visitor operation but can just catch boost::bad_get exceptions.

STYLE: Split XdmfArray.tpp from XdmfArray.hpp --- this will hold template implementations for XdmfArray instead of stuffing them all in XdmfArray.hpp (merely a style difference).  Do some minor formatting on some other files.

unnecessarily duplicated functionality.

Conflicts:
	Xdmf.py
	XdmfPython.cpp