Use string child names for non-list nodes

Implementation needs some polishing.

Improve AST_CLOSURE_VAR implementation

* Simplify code by combining nearly completely duplicate function
* Add AST_CLOSURE_VAR to generate_ast_data.php
* Add test
* Adjust README

Add virtual AST_CLOSURE_VAR node Without this you couldn't distinguish a by-ref closure use var

Update AST data

Update AST data

Remove stay whitespace in ast data generation

Initial commit