change req.timeout to public and add min deadline in pipeline

[fare83]

change req.timeout to public for Do method support timeout;
add timeout in clientGetURLDeadline;
add min deadline in pipeline

[erikdubbelboer]

Can you explain why you need Request.Timeout to be public?

[fare83]

when i use hostclient.Do ，i can't set timeout

[erikdubbelboer]

But that internal timeout is only used as a timeout to acquire a connection if you have MaxConns set. What I would actually much rather do is make that timeout equal to WriteTimeout and completely get rid of req.timeout.

[fare83]

I want to set timeout for current request, but writetimeout is for all host and request.

[erikdubbelboer]

What do you think of this instead: #1346
HostClient already has DoTimeout and DoDeadline. What this pull request does it just make them use req.timeout instead of the separate goroutine that I have always hated.

[fare83]

#1346 LGTM