Closes #68; Added option accessor / mutator

I am fairly confident that this will work, but I would feel a lot better if we had unit tests in place to make sure it continues to do so. For the time being I'd like to get it in as an experimental / untested feature. Might think about bumping up #24 into release 0.6.0.

@bontibon - Can you give this a quick look for me?
I see now that nesting actual objects works.  I guess what I suggested before is actually a feature request, if you think it's necessary.