1.1.12

New message handler API

• Received messages are not passed in the handler arguments. Recv() must be called in the handler
• Timer returns timespec instead of string
• Riaps MessageBuilder<> and MessageReader<> are introduced
• On errors Recv()/Send() functions return ZMQ Error number too
• Adjusting coding style according to Google C++ guide
• Add HandleReinstate function to pybind interface