Update Binaryen for 2020

[dcodeIO]

In celebration of the new year, this updates our Binaryen bindings to include fireworks.

• Update bindings
• Attempt to avoid versioning issues on the web
• Integrate new reference types features (ref.null, ref.is_null, ref.func)

[dcodeIO]

Last commit also adds a little SDK to use on the web, primarily targeting WebAssembly Studio, that glues asc to the specific Binaryen version it requires. If that works as expected, we can get rid of conflicts by using the SDK in studio's setup code.

[dcodeIO]

What's left is ref.func, which we don't have a good story for yet. For instance, we can't do

var some: anyref = someFunc;

yet due to someFunc being represented by a function table index, while ref.func wants a static function index (respectively function name in the Binaryen API). Perhaps we can compile that differently, will take a look.

[dcodeIO]

Ok, that turned out to be easier than expected :)