Don't start requesting more peers if connected to PEX-enabled peers.
Added socket based interruption of threads. Use '--enable-interrupt-socket' configure option to enable.
Made interrupt socket nonblocking and added a way for rtorrent to figure out if it needs to handle SIGUSR1.
Added thread names using pthread_setname_np.
Fixed interrupt sockets being added to the write event, not the read event.
Added a void poitner to the DiffieHellman class when OPENSSL isn't defined.
Only poke the interrupt socket once, rather than looping as is required by the signal handler version.
Changed the order in which pthread_setname_np argument types, darwin have proper compilers so assume this platform properly detects the right parameters.