This release adds a single new feature: support for length(array) in addition to length(string) (#176). Calling length() on an array is quite useful and is supported by all other awk versions (onetrueawk, Gawk, mawk, busybox awk, frawk). In addition, it's been accepted for inclusion into POSIX, though not yet added to the main spec (which seems to take forever).
This release also includes a complete rewrite of the type resolver (#175). Before the code was quite messy and hard to read, now with the two passes I think it's easier to understand and work with. It was certainly easier to add the length(array) feature with the rewritten resolver than before.