There are various forks that added fixes/patches to the codebase, but there isn't any pull request to integrate them into this project.
We should analyze what can be integrate and add them accordingly.
Among the forks:

• https://github.com/stripe/goproxy ✅
• https://github.com/Windscribe/goproxy
• https://github.com/abourget/goproxy ✅
• https://github.com/SpectoLabs/goproxy (we are violating RFC7230 too, as explained in this issue in another project: HTTP 204 No Content with Transfer-Encoding header violates RFC 7230 Pylons/waitress#165) ✅
• https://github.com/forensant/goproxy ✅
• send Connection: close header to client only when needed #514 (to avoid adding an header to each request when not needed)

Replace http constant values with their HTTP equivalent.
e.g. "HEAD" -> http.MethodHead ✅