add match() to return the actual scored characters

`match(string, query)` returns a list of strings showing the matched characters of the form `[unmatched1, matched1, unmatched2, matched2, ..., unmatchedN]` and is used to highlight matches in the fuzzy-finder.

This is related to https://github.com/atom/fuzzy-finder/pull/39

Screenshot:
![image](https://cloud.githubusercontent.com/assets/253202/3085559/11675ca6-e514-11e3-8208-de7e141eef41.png)

Animated:
![fuzzy-highlights](https://cloud.githubusercontent.com/assets/253202/3085570/411e7e70-e514-11e3-9000-fd5952e43d39.gif)