Support changing the name of an existing node

[awashbrook]

@krispo fantastic library, I have been looking forward to trying it for some time now. The ability for non-developers to edit the JSON tree rather whilst making it impossible to make syntax errors with a text editor approach is very appealing.

However, their appears to be no workflow to change the name of an existing key in a given object, only when adding the key?

Please clarify? This is a blocker for my work.