WIP: AST{Reader,Writer} alternative

[jansvoboda11]

Prevent module redefinition errors, fix memory leak

[dblaikie]

("Simple" tends to be an over used/overly vague term and may become less correct over time - if there's some more descriptive term that explains the difference between the old and newer one it'd be awesome to use - but yeah, sometimes "Simple", "New", etc, is just the way it goes :))