`gemini_open' is now `gemini_connect'
`gemini_close' is now `gemini_fini'
`gemini_connect' will try to use the `socketfd' struct member, if valid.
`gemini_read' now returns 0 whenever the response header has been read.
`gemini_read' no longer handles user-input (status 10) itself.
`gemini_connect_query' has been added so callers can handle user-input.
`libgeminiclient.c' no longer needs `readpassphrase' and `libbsd'.