* Add support for HTTP/2 and SOCKS proxies to HttpxDownloadHandler.
* Update the docs.
* Trim the tables.
* Restore lost wording.
* Handlers docs improvements and fixes.
* Run mitmproxy-based tests for every handler and improve them.
* Fixes for H2DownloadHandler.
* Revert "Fixes for H2DownloadHandler."
This reverts commit bcdbd097cd.
* Add TestHttpsProxy for HTTP11DownloadHandler.
* Use the configured context factory in ScrapyProxyAgent.
* Reword.
* Reword.
* pragma: no cover for H2DownloadHandler proxy code.
* Raise an exception for HTTPS proxies instead of using HTTP.
* Remove non-working proxy support and explicitly forbid HTTP.
* pragma: no cover
* Add a docs note about HTTPS proxies.
* Rename ScrapyProxyAgent.