Fixed all (well, most) string memory leaks in the parser. I've run
automated tests on all the demos and benchmarks, and I did not see
anything suspicious (no crashes, double frees, etc.)

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*********** Pretty please, please give this version **************
*********** a try, especially on files with lots of **************
*********** loops, includes, arrays of variables,   **************
*********** etc., and report any problems. Thanks!  **************
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