Bug#764357: non-free file in package

[Tsukasa #01 (OI)]

I can't directly contribute to ssdeep because I saw the non-free source
code of edit_dist.c. So I decided to tweet this problem.

After I tweeted this problem on Twitter (in Japanese), @kikairoya (who
has not seen the source code of ssdeep and/or trn) wrote a program to
compute ssdeep version of Levenshtein distance.  He says he licenses the
source code under the terms of Boost Software License, version 1.0
(compatible with GPLv2+). I didn't even tell him the interface for
ssdeep so slight modification will be needed.

https://gist.github.com/kikairoya/58f996c36210ffc31e79

Anyway, is there any reason to make replacement cost in the ssdeep
version of edit_dist.c 3? I think a replacement will always have a cost
of 2 (because this can be achieved by character removal and insertion).

Thanks,
Tsukasa