Title: Adding convenience methods to Issue-66

Hi Everyone,

Assuming that Issue-66 is resolved today, I've been thinking about adding some convenience methods, to make this functionality more convenient.

The first thing I'd like to do is define what happens when an object from one context is passed to a helper in a different context. Using our usual notation where O1 is an object in context C1, etc, the case that I think is most important is:

C2.getXMLHelper().save(O1)

Should be logically equivelant to

O2 = C2.getDataHelper().project(O1); C2.getXMLHelper().save(O2); O1 = C1.getDataHelper().project(O2);

In all the different flavors of save. One advantage of using such functions would be that, at least as far as the user's concerned, O1 never enters an undefined state...I'm worried about bugs if the user forgets the second project. The user would also not have to worry about the "cast back" being invalid. Since O2 was never modified, the cast back must always work.

Slightly more controversial might be:

O2.set("x",O1);

I think this is equivalent to

O2.set("x",C2.getDataHelper().project(O1));

Just giving some notice, since, if we do resolve 66 today, I'd like some clarity about the next steps in this direction.

Best Regards, Ron