Add websocket.CloseStatus

Will make it much more convenient and less error prone to access
the StatusCode of a *CloseError.

Switch CI to Typescript

Integrated into the appropriate existing steps.

Significantly faster locally since **everything** runs in parallel.

Also much easier to maintain than bash.

Upload coverage.html from test.sh as an artifact

Improve usage of math/rand versus crypto/rand

math/rand was being used inappropiately and did not have
a init function for every file it was used in.

Fix WASM Subprotocol selection

Subprotocols didn't work with WASM at all before.

Very annoying.

Should prevent the sporadic failures in CI.

Closes #151

Closes #150

Fix unaligned 64 bit atomic loads on 32 bit platforms

- Also allows SetReadLimit to be called concurrently which is a nice
  touch

Closes #153

Fixes from @albrow's Wasm review

Cleanup README language

Implement more of the API for WASM

Realized I can at least make the Reader/Writer/SetReadLimit methods
work as expected even if they're not perfect.

Updates #88