Increase compatibility

[Eseperio]

This library works fast, but its compatibility is very limited. Using a few lines like in old fast-levenshtein allows the algorithm to be used with AMD, requireJS, Web workers and commonJs.

[gustf]

Sorry for (very) late reply.

Thanks for your input.

I don't think this is the right way to go for this library at this point. My plan is to use native es6 modules sometime in the future.

If you don't agree you are more than welcome to make a PR and I might reconsider :)