Made the transposition operator left associative as it was leading to parsing errors when it was nonassociative and being used along with other row operators
Changed some structural comparisons to name comparisons to avoid out_of_memory errors when comparing function definitions; to_sexpr on a let only does the first pass on the let declarations now, as doing the second pass at the same time was failing since we hadn't done a second pass globally yet; the second pass on a let expression now occurs within walk_decl_second