This'll allow binding multiple signatures of a JS function as well as otherwise
changing the name of the JS function you're calling from the Rust function that
you're defining.
Closes#72
Along the way remove the namespace in Rust as this ended up causing too many
problems, alas! The `js_namespace` attribute now almost exclusively modifies the
JS bindings, hence the "js" in the name now.
This commit renames the `static` attribute to `namespace` and simultaneously
reduces and expands the scope. The `namespace` attribute can now be applied to
all imports in addition to functions, and it no longer recognizes full typed
paths but rather just a bare identifier. The `namespace` attribute will generate
a Rust namespace to invoke the item through if one doesn't already exist (aka
bindign a type).
This commit migrates from `wasm_bindgen!`-the-macro to
`#[wasm_bindgen]`-the-attribute. The actual mechanics of the macro are
relatively simple in just generating some shims here and there, but wrapping
everything in one huge macro invocation can often seem intimidating as it gives
off this feeling of "oh dear anything can happen here!" Using an attribute
should curb expectations much more greatly of "oh there's just some extra stuff
happening behind the scenes".
The usage is otherwise relatively straightforward and close to what it was
before, but check out the DESIGN.md/README.md changes for more info!
