TCPSocket.close() now accepts "flush" parameter, which delays actual close until all pending data sent

 * noc-activator.conf accepts [activator]/max_pull_config parameter
 * activator returns ERR_OVERLOAD when pull_config limit reached
 * SAE  performs next_pull randomization in case of failure
 * SocketFactory.count_subclass_sockets method

Do not crash when socket closed before exception raised. Kill not crashed when child already was killed

loop() no longer crashes on signal received

Early handle_read forces FSM state mess on Solaris platform

 * FileWrapper - mimics socket behavior for regular files and pipes
 * PTYSocket  - forks and communicates separate processes
 * Socket.TTL - attribute limiting socket maximal time to live (in seconds)
 * Socket.is_stale - Function to detect whether socket is stale and can be purged
 * SocketFactory constructor now accepts optional tick_callback argument which will be called every second in run() loop
 * SocketFactory.run now accepts optional run_forever argument