add ringbuffer
modify net step 1
add log to syslog server
 add func StringUtil::strtok
	modified:   iocp_event.cc
	modified:   iocp_event.h
modify net library step 2
	new file:   log/log_stdout.h
modify net library step 3
modify net library step 4
	modified:   event.h
modify net library : server mode done
finish modify net library v2.0