Evaluate WebAssembly options and decide on path forward

[dfellis]

The JS output and runtime shim do not gain any of the parallel computation benefits of Alan.

WebAssembly does have multithreading on some browsers so it should be possible to bring nearly all of the benefits of Alan to them (no running your own web server in your web browser, though!)

However, there are multiple approaches that could be taken here and they should be comprehensively evaluated before taking a leap in any particular direction.