* Rate: don't sleep if sleep exceeds context deadline
* Httputil: add Client.Timeout
* Bot: set default API timeout to 5 minutes
* Rate: reduce calls to time.Now in Acquire
* API: Optimize to use deadline instead of recalculating
Co-authored-by: diamondburned <datutbrus@gmail.com>
This commit updates Retry-After to be seconds-accurate instead of the
previous millisecond-accurate. Another issue (#153) is opened to get a
more accurate number, which is in the JSON body instead of the header.
This commit also removed the rate limit precision header. It also uses a
more accurate calculation algorithm to derive the reset time.