Make origin available to the websocket server

• Make the value of the Origin header visible to the server, via LogicalOverflow.
• Remove echo testing (the external echo server no longer exists).
• Switch from deprecated lsh to ash.

Better handling of broken connections

This version fixes a bug where an abnormally closed connection wouldn't mark the websocket as closed before calling websocket-on-close. With this fix, clients can detect the websocket as closed in this function.

Testing changes and minor functionality fixes

• Made all tests runnable via ert, and re-introduced the python-based webserver test.
• Fixes an issue with infinite loops when websockets get an error. We now do not attempt to reconnect when the connection is dropped.
• Fixes an issue with nowait connection timings.
• Fixes an issue with handshake protocol that was an issue on some servers.

Thank you to contributors @yuya373 @xuchunyang @xhcoding @sten0.

More liberal header acceptance

Accept Sec-Websocket-Accept header, a variant of the Sec-WebSocket-Accept that is used in the spec. This header variant is in use and should be supported.

Async connections, 32-bit fix

Support nowait connections, which will return from websocket-open without necessarily waiting on a connection.

Fix an issue for a recent 32-bit emacs failure with a too-large constant.

Contributors:
@yuya373 and Paul Eggert.

1.9

This release adds the ability to set custom headers for websocket clients.

1.8

Fix issue with Emacs querying users about exiting network processes. Thanks https://github.com/alpha22jp for the fix.

v1.7: Fix issue with handling multibyte characters.

Multibyte fixes and minor code formatting changes.