Browser support + marginally smaller modules (#1)

* Shave ~20 bytes from math.js file

This is just a small micro-optimization using converge and inline.always
to remove a few bytes off of the final .wasm size. Sadly, we can't use
"shrinkLevel": 3 since that gives imprecise results.

* Fix the message for the 10^-5 test

This confused me for a couple minutes when testing out "shrinkLevel": 3.

* Use `fetch` and `WebAssembly.instantiateStreaming`` to support browsers

Browsers don't have Node.js's Buffer, nor do they have any reasonable
way to decode base64. Luckily, `WebAssembly.instantiateStreaming` allows
using the results of `fetch`, which in turn can accept base64 data URIs.

first commit