Changed to unpack given argument on call-next-method when optional argument was passed.
Renamed socket.c and socket.h to avoid file confiliction with STKlos.
(I think this is more for STKlos' problem but it's easy for me to fix it since
 this header is not used other than sagittarius--socket)

--HG--
rename : ext/socket/socket.c => ext/socket/sagittarius-socket.c
rename : ext/socket/socket.h => ext/socket/sagittarius-socket.h