Create chainable similar to json-operator

[mandricore]

Play with json-operator to get a feel for the API
The objective is to create a similar API for querying/operating on the AST.
See #2 for details

The API should make it easy to perform common high level AST operations, such as:

• Create/delete class
• Create/delete function (or function inside a class, ie. within scope of an identifier)
• create/delete const in scope
• add/remove import/export of a module
  ...