Fix Stack_overflow for filtering a file

[westpaddy]

The current implementation rarely raises the Stack_overflow exception for filtering some particular files. I encountered the situation with a file containing a rather long [[ ... ]] being parsed.

This fix replaces non-tail-recursive functions related to the problem with tail-recursive ones. I believe this fix causes minor performance issues for at least filtering files the current implementation can handle because only a short list is dealt with in such cases. The fix may be more efficient if we well understand the algorithm, though. For example, we can remove List.rev if a list used in the algorithm is order-irrespective.