adds an xml memento serializer converter to intercept and restore the management context, as that is inserted in various places e.g. for DSL;
also several related fixes and tidies, moving anonymous inner classes to be named or statics, to make the memento xml a bit nicer.
updates xstream to 1.4.7. this is not needed but it seems a bit faster and friendlier (though i can't put my finger on either...).
undo the MapConverter retry-with-copy, and other items as discussed in code review
Merge pull request #1457 from ahgittin/fix-attr-when-ready-rebind-1422

Fix attr when ready rebind 1422