Add a sort function for the search function

Hi !

I've been using this library with rutorrent for a couple of days now, but the subtitle downloaded is, most of the time, not the one expected (when I use a file as an input)

So, I've added a function that compute a "matching score" for each result. Then, it will sort the results of the search query according to that score.

I used this library to compute the score : https://github.com/Glench/fuzzyset.js 

Let me know what you think about it !