A reactive spider in Java.

Temporarily called "amygdala", until I come up with a better name,
because amygdalas make people reactive and are activated by spiders.
Not related to amy jo; not related to a RESTful HTTP client for
JS-powered web apps; not related to Wordpress.

Inspired by Meteor's
[Deps](https://github.com/meteor/meteor/blob/master/packages/deps/deps.js)
as well as, obviously, Fran, FRP in general, Gray and Reuter, and
[RxJava](https://github.com/Netflix/RxJava/wiki).