* Regenerate the list of features for the crate given recent
improvements, enabling some more types to be bound.
* Add feature gates for the `css` and `console` namespaces (modules),
gating the APIs by default. Now `web_sys` has zero APIs unless they're
requested.
* Improved the "required feature" documentation for `struct` types to
not list parent classes and mention just the `struct` type instead.
This commit is a large-ish scale reorganization of our examples. The
main goal here is to have a dedicated section of the guide for example,
and all examples will be listed there. Each example's `README` is now
just boilerplate pointing at the guide along with a blurb about how to
run it.
Some examples like `math` and `smorgasboard` have been deleted as they
didn't really serve much purpose, and others like `closures` have been
rewritten with `web-sys` instead of hand-bound bindings.
Overall it's hoped that this puts us in a good and consistent state for
our examples, with all of them being described in the guide, excerpts
are in the guide, and they're all relatively idiomatically using
`web-sys`.
