Update std lib

For compat with Deno 1.9

Update to latest std lib, return socket from handleUpgrade method (#12)

* Update std lib to v0.89.0 for modern compatibility

* Return socket from handleUpgrade method

For compatibility with server frameworks such as abc.

Update to latest std lib, return socket from handleUpgrade method (#12)

* Update std lib to v0.89.0 for modern compatibility

* Return socket from handleUpgrade method

For compatibility with server frameworks such as abc.

Update to latest std lib, return socket from handleUpgrade method (#12)

* Update std lib to v0.89.0 for modern compatibility

* Return socket from handleUpgrade method

For compatibility with server frameworks such as abc.

Fix typo in README

Fix wrong boolean type in queue

Add examples for using with existing http servers

Fixes #2

Add some tests

Change MuxAsyncInfiniteIterator to a "queue"

The async multiplexer was unnecessarily complex.
It has been replaced by a simple queue only incorporates the
asynchronous queueing logic of the original multiplexer, and
skips the iterators.
Fixes #4

Update README with a FAQ and formatting