iteration or callback support

[casperdcl]

Support

• content streams (like requests.Response.iter_content), or
• per-chunk callbacks (like urllib.urlretrieve(..., reporthook=...))

[casperdcl]

I think this comes down to creating a new class HTTPResponseCallback(http.client.HTTPResponse):

class HTTPResponseCallback(http.client.HTTPResponse):
    def __init__(..., callback=None):
         self.callback = callback
         ...
    def _readall_chunked(self):
		...
        while True:
            ...
            if callback:
				self.callback(len(chunk))

class HTTPConnectionWithTimeout(http.client.HTTPConnection):
    response_class = HTTPResponseCallback