[tests] Improvements in fuzzycomparevtu

- Parameters with more than one component are split into components for
  comparison
- The absoulte criteria gets scaled with the maximum absolute value in
  the parameter set
- It is possible to pass a zero threshold, i.e. the threshold under which
  values get treated as zero, for each parameter or
  parameter component via runtest as follows
  --zeroThreshold = {"vel":1e-9,"bla":10}
  The format is a python dictionary except single quotes are not allowed
  (because it uses json)
- More verbose output


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@15254 2fb0f335-1f38-0410-981e-8018bf24f1b0