mrg: socket API refactoring branch into main

src/net/async_fd.hpp

src/net/async_server.cpp

src/net/async_server.hpp

src/net/client_factory.cpp

src/net/client_factory.hpp

src/net/connection_client.cpp

src/net/connection_client.hpp

src/net/connection_line_buffer.cpp

src/net/connection_line_buffer.hpp

src/net/ioqueue.hpp

src/net/iorecord.cpp

src/net/iorecord.hpp

src/net/sock_address_factory.cpp

src/net/sock_address_factory.hpp

src/net/socket_utils.cpp

src/net/socket_utils.hpp

src/net/socketaddress.cpp

src/net/socketaddress.hpp

src/net/tcp_client.cpp

src/net/tcp_client.hpp