Review new DocumentHandle.java and TestDocumentWorkflowImpl with respect to SCXML states model and hints evaluation

Hi Frank,

Could you make a start with reviewing the new SCXML DocumentWorkflow features?
I created this sub-task specifically for looking at (only) the new DocumentHandle model class and the new SCXML states and hints evaluation, using test SCXML resource test-document-workflow.xml.

Implementation of this is still ongoing, but very much incremental, so as of this moment I think the SCXML parallel states "status", "editing" and "request" should be reviewable already.
Implementation of the still to be done states ("publish", "depublish" and "version", "terminate" and "copy") should follow soon as well.