Add Damerau–Levenshtein distance

[tomspencer]

Hello, I noticed that utbox already has a Levenshtein distance function, which is great, but for some use-cases Damerau-Levenshtein yields more useful results.

Would you be open to adding Damerau–Levenshtein?

[mayurah]

JellyFisher https://splunkbase.splunk.com/app/3626/#/details solves that requirement.