Simple parallel algorithm for creating edit lists

[nickkeers]

Fixes #4

Hello! Following your issue about suggesting words quicker I've written a quick addition to compute your word lists in parallel, as I thought it'd be a quick win in terms of performance as you were computing the 4 word list functions (deletion, transposition, alteration, insertion) inside of a lists:usort.

So i've pulled those out to work in their own processes and then send on the results when they're done, collecting them into an accumulator and sorting when finished.

I did a quick check and from an average of 6 runs it computes

check:known("seach") in 2.3s

[nickkeers]

Also, I formatted the code a bit, sorry if that's annoying!

[mishal23]

Good Work @nickkeers !
A good thought put upon!
Would be glad if the time decreases more!