run actual chan read/write;computations in go routine; otherwise deadlock
fix all the bugs!
deal properly with requested timeranges
more awesome

* add derivative function
* be more graphite-like. use N target query params
* support a way for dependent functions to tell their dependcies
  which range they need (not necessarily just from-until!)
* packages, refactor
simpler, more examples
bugfix: support floats. like scale(foo,1.43)
readme update