Fix printing negative server conn count in debug message.
Add tunnelAllowedPort option, check before serving CONNECT request.
Comment: why can't require authentication for PAC.
Store only hostPort in server connection.
Share server connection between clients.
Close server connection only once in doConnect.
Merge branch 'feature/share-conn' into develop
Remove incorrect invalid response check.
Add tunnelAllowedPort option explanation in sample rc.
Set server conn clean up interval to default server timeout.
Simplify close server conn after remove channel from map.
Use close channel trick in copyClient2Server.

Learned this from Dave Cheney's article,
http://dave.cheney.net/2013/04/30/curious-channels
Print connection pool message with client info.
Tweak debug message.
Only show auth response body if verbose is true.
Remove unnecessary request check in sendBody.
Increase client connection timeout to 15s.
Skip possible trailers in chunked body.
Report precise error message to client.
Refactor calcRequestDigest.