rewriting config_*, xmalloc_fget*

[Cathey, Jim]

There are exactly two characters (of an unsigned char)
that cannot be in a Unix filename: '/', which is the
path component separator, and '\0'.  Everything else,
including newlines and spaces, is perfectly legal
in a filename, though perhaps incredibly annoying
to deal with if present.  The \0 delimiter was really
the only choice for -print0.  Don't really see a context
where _both_ delimiters are meaningful in the same file
stream, though.

-- Jim