using CursiveClojure
bump dependencies to latest
Trying to port Elm's signals

Mainly working from the Concurrent ML implementations
provided in the following papers:

Elm: Concurrent FRP for Functional GUIs (Czaplicki 2012)
Asynchronous Functional Reactive Programming for GUIs (Czaplicki & Chong 2013)

The code began as a more direct port of the CML code
from the 2012 paper, but has since diverged to fit
Clojure a bit more nicely.

The approach I've taken here kind-of works, but I'm
encountering surprises with the timing of core.async
channels.