Complete rewrite

This is a complete rewrite of HLearn from previous versions. The interface is much more stable, but still not fully developed. The main selling point of this release is the fast nearest neighbor queries provided by the cover tree data structure and hlearn-allknn executable.

1.1

This release demonstrates the first basic experiments in an algebraic interface for machine learning. Unfortunately, Haskell's standard libraries don't support what HLearn needs, so the interface is clunky and hard to use.