Add datagram class for connectionless sockets
Add socket request class, will add socket option metadata
Abandon the socket request class idea, use socket options class instead
Update documentation tags
Move AFNetworkSocketOption to the correct place
Update socket opening calling convention
Add support for applying the socket options provided at init time, make the debug SO_REUSEADDR an option added if compiled in debug configuration

Fix leaked file descriptors if there’s an error configuring or binding

Use recvmsg to read data and metadata from the socket
Merge remote-tracking branch 'origin/master'