generic support underneath Complex type

[sritchie]

Right now, the Complex datatype is based on

• Double in Clojure,
• js/Number in Clojurescript due to the Complex.js dependency

josdejong/mathjs#694 has some discussion about the problems this has created in math.js. The big one is that you can't extend complex arithmetic to arbitrary precision.

We COULD probably do this if we rebuilt Complex in Clojurescript, on top of the generic arithmetic. (I think you might be able to get complex matrices for free??)

https://github.com/infusion/Complex.js/blob/master/complex.js is not that big of a library. porting it over to cljc, and backing it with generic operations, would be a really nice project.

[sritchie]

Closed by #151.