in that it does not resolve link
        names in the middle (ex. /x/y/z, y is a link to w - realpath on z
        will return /x/y/z, not /x/w/z).

        @return: L{FilePath} of the target path.
        @rtype: L{FilePath}
        @raises LinkError: if links are not supported or links are cyclical.
        z!Cyclical link - will loop forever)