More unit tests, func signatures changed
callback signature changed
tcp_skeleton -> net_skeleton
PF_INET -> AF_INET
Setting last_io_time in ns_add_sock() and ns_connect()
squashed warning
re-added signal.h
Handling NS_CLOSE in client_handler()
add_to_set(): fix around non-negative SOCKET on Windows
Merge branch 'master' of https://github.com/cesanta/net_skeleton