Make RKellyParser use the Associator.

Inside RKellyParser:

- Invoke RKelly.
- Adapt its output with RKellyAdapter
- Set the correct range for root node.
- Pass the adapated AST to Associator.

Change RKellyAdapter to:

- Create root "Program" node.
- Adapt the comment nodes inside this root node.
- Adjust the range end by one - so it matches the esprima way.
- Include line number to the adapter range.