[request] Add countdown to captcha refresh.

[popman]

Add a countdown to the time when the currently loaded captcha will refresh, maybe at the top right corner of the captcha section.

This would remove a lot of the cases of the captcha resetting while it's being typed.

[ihavenoface]

The recaptcha script isn't controlled by 4chan X so I'm not sure about the timeouts. I will check up on that.