* this preserves principle of least surprise when dealing with files that

 * this preserves principle of least surprise when dealing with files that
   are reachable via many path strings.  i.e. when $PWD=/base/dir the
   following files are the same:

        /base/dir/x.rrd
        x.rrd
        ../dir/x.rrd

 * for performance, absolute paths (starting with '/') are not resolved.
   this reduces the number of stat(2) system calls.

git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@1604 a5681a0c-68f1-0310-ab6d-d61299d08faa