1. Generally we should prefer to use the `log` crate.
2. I very often accidentally commit `eprintln`s.
When we should use `println` or `eprintln`, it's not too bad to be a bit
more verbose and ignore the lint rule.
Node HTTP/2 was using the default h2 `Bytes` datatype when we can be
making using of `BufView` like we do in `Deno.serve`.
`fetch` and `Deno.serverHttp` can't make use of `BufView` because they
are using `reqwest` which is stuck on hyper 0.x at this time.
Adds `buffers` to the `Deno.jupyter.broadcast` API to send binary data
via comms. This affords the ability to send binary data via websockets
to the jupyter widget frontend.
