Generic Enumerable and Collectable implementations

[turion]

The Enumerable and Collectable protocols can be implemented for Hallux.Internal.FingerTree, as far as I understand. For some operations (like count on Seq) there are more efficient specific functions in the special cases, but sometimes it would be nice to reuse generic functions when implementing a fingertree with a custom monoid.

[turion]

I can try and submit a PR if you're interested.

[thalesmg]

Sure! I guess there'll be a need for special cases like IntervalMap's into and Seq's count as you have noted. But if you believe there can be some reuse for those and other use cases, then it sounds like a good idea.