Created NET_FIDO_ASCII net type for ASCIIZ (e.g. 5D) FidoNet addresses.

Created 'locked' field in smb_t used internally in smblib.c so that
smb_addmsghdr() will not try to re-lock an already locked SMB header,
eliminates a potential hole between calling smb_unlockmsghdr and smb_addmsghdr.