v1.3.0

API changes in version 1.3 compared to 1.2

• Limits is no longer an interface but not a plain struct with fields
  you can set and edit. This simplifies the code and makes the API easier to use.

• Limits now exposes wait times as BufferMinWait, BufferMaxWait,
  StreamMinWait and StreamMaxWait. These values default to the same as in
  Gotalk 1.2 (500–5000ms.)

• The string message of ErrSockClosed has been changed to "socket closed"
  (was "socket is closed")

Other changes:

• Fixes a race condition with closing sockets which could lead to CloseHandler
  being called twice in case two user goroutines would call Sock.Close()

• Fixes a race condition that could lead to a deadlock when sending requests and
  waiting for responses.