Parser appends on the wrong side of lists.

[Renelvon]

When reducing rules that result to lists or sequences, the parser currently appends elements at the start and not the end of lists. This is a possible performance issue.

Proposed fix: Make the parser append at the end of lists, but reverse the said lists just before embedding them inside the AST Nodes. This will maintain program order.

Accompany with appropriate unit tests demonstrating correctness of patch.