universal.c - utf8::downgrade($x,FAIL_OK) is not supposed to treat FAIL_OK as an integer
hv_func.h - fix seed initialization in sdbm and djb2 hashing algorithms.

In a previous commit I added code to "mix in" the length of the
string into the seed used by these functions, to avoid issues with
zero seeds, and with the hope that it makes it harder to create
multicollision attacks against these hash functions.

Unfortunately when I restructured the seed logic for the inline
functions in hv_func.h I messed it up, and these hash functions
were broken. I never noticed because they are both such bad hash
functions for our needs that I never built with them, and we have
no infrastructure to make it easy to test building with non-standard
hash functions so it never got automatically tested. Hopefully
at some point someone will find a round-tuit and teach Configure
about selecting alternate hash functions.
Hash::Util - fixes to hash stats and add bucket_stats_formatted()

* we should do the mean/stddev on the on the occupied buckets not all buckets.

This was always intended to the be average chain-length, which implies
that empty buckets with no-chains at all are excluded.

* Add bucket_stats_formatted(), bump version

Creates reports like this:

    Keys: 500 Buckets: 314/512 Quality-Score: 1.01 (Good)
    Utilized Buckets: 61.33% Optimal: 97.66% Keys In Collision: 37.20%
    Chain Length - mean: 1.59 stddev: 0.81
    Buckets 512         [0000000000000000000000000111111111111111111111122222222222233334]
    Len   0 Pct:  38.67 [#########################]
    Len   1 Pct:  34.57 [######################]
    Len   2 Pct:  19.53 [############]
    Len   3 Pct:   5.47 [####]
    Len   4 Pct:   1.17 [#]
    Len   5 Pct:   0.59 []
    Keys    500         [1111111111111111111111111111111111111111222222222222222222333334]
    Pos   1 Pct:  62.80 [########################################]
    Pos   2 Pct:  27.40 [##################]
    Pos   3 Pct:   7.40 [#####]
    Pos   4 Pct:   1.80 [#]
    Pos   5 Pct:   0.60 []

* Make it possible to get stats on PL_strtab

* bump version to 0.17
regcomp.c - cleanup the ahocorasick start class logic so it more self-documenting

The logic of setting up an AHO-CORASICK regex start class was not fully
encapsuated in the make_trie_failtable() function, which itself was
poorly named. Merged the code into make_trie_failtable() and renamed
it to construct_ahocorasick_from_trie().