New failure detection algorithm for ng_one2many

I wrote new failure detection algorithm based on heartbeat signal for ng_one2many node. Features: - automatic detection of failures; - all subnet containing failed element marked as failed. Therefore packets sended from other hosts to host, holding failed element, wouldn't lost; - automatic det

ng_one2many heartbeat algorithm for LAN fault tolerance

mber of timeouts for failure determination statistics Default values are timeout=10 and period=10. Two new node messages: "gethbconfig" and "sethbconfig {timeout=X period=Y}" for getting and setting heartbeat algorithm params. Au