Correct local integer values for error treatment to be grabbed from grouped...

Correct local integer values for error treatment to be grabbed from grouped parameter [Impet] instead of without groups. Approved by Markus

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@9090 2fb0f335-1f38-0410-981e-8018bf24f1b0