* reverse_proxy: Initial attempt at H2C transport/client support (#3218)
I have not tested this yet
* Experimentally enabling H2C server support (closes#3227)
See also #3218
I have not tested this
* reverseproxy: Clean up H2C transport a bit
* caddyhttp: Update godoc for h2c server; clarify experimental status
* caddyhttp: Fix trailers when recording responses (fixes#3236)
* caddyhttp: Tweak h2c config settings and docs