hackage release

[ekmett]

This would be a lot more use if it was on hackage! ;)

[gereeter]

Ah, right, I forgot about this again. My plan was for this to get on hackage via haskell/containers#340, which is where the latest development is (including some pretty big speedups). As far as I'm aware, the only thing blocking that is that I haven't written more explanatory comments, and since I sort of forgot about it, I never got around to that.

That said, I guess I could release this as a separate package in order to provide WordMap and possibly an early version of the faster IntMap. I'm not completely clear on any licensing issues there may be, since I definited directly copied at least some comments and some code directly from containers.

[treeowl]

@gereeter, we in containers land would love if you'd pick this back up.