* some initial support for IPv6:

	* some initial support for IPv6:

	* socket.c (scm_fill_sockaddr): improve the argument validation.
	don't allocate memory until all args are checked.  instead of
	unconditional memset of soka, try setting sin_len to 0 if
	SIN_LEN is defined.  add support for AF_INET6.  define FUNC_NAME.
	(scm_socket, scm_connect): extend docstrings for IPv6.
	(scm_init_socket): intern AF_INET6 and PF_INET6.