add component
	new file:   lib/sl_component.lua
	modified:   lib/sl_core.lua
	new file:   lib/sl_object.lua
	modified:   test/Makefile
	new file:   test/test_component.lua
  add component path for other objects
	modified:   lib/sl_component.lua
	modified:   lib/sl_core.lua
	modified:   lib/sl_event.lua
	deleted:    lib/sl_object.lua
	modified:   lib/sl_pipe.lua
	modified:   lib/sl_signal.lua
	new file:   lib/sl_socket.lua
	modified:   pli/Makefile
	modified:   pli/sys_lua.c
	modified:   test/Makefile
	new file:   test/test_socket.lua
  refine
	modified:   lib/sl_component.lua
	modified:   lib/sl_event.lua
	modified:   lib/sl_pipe.lua
	modified:   lib/sl_signal.lua
	modified:   lib/sl_socket.lua
	modified:   test/test_socket.lua