cookie auth, json inputs, json extra params

[blackmad]

• eslint fix: make it explicit that this project uses single quotes
• fix trailing spaces in some README.md examples + get rid of junk from my old prompt
• add ability for header auth to specify what header it should use (defaults to Authorization still, but we use a custom header "cookie" for our internal api)
• add a new input type - input_json - which expects jsonl request bodies, one per line
• detect if extraParams are meant to be parsed as JSON (simple heuristic - does it start with a '{')
• be more permissive about constructing valid urls out of base url + endpoint (previously, it was easy to make urls that looked like http://host:port//endpoint or http://host:portendpoint and many servers hate the double slash)
• output to a file if html or json output specified and output is a tty (don't do this if it's being redirected)

[abbottdev]

Having a configurable body payload would be awesome. Any chance of getting this merged?