update
	modified:   lib/sl_core.lua
	modified:   lib/sl_event.lua
	modified:   lib/sl_pipe.lua
	modified:   lib/sl_scheduler.lua
	modified:   lib/sl_signal.lua
	modified:   lib/sl_simtime.lua
	modified:   lib/sl_simulator.lua
	new file:   lib/sl_util.lua