[co2] Adapt parameters to new gridcreator interface

The gridcreator interface was slightly changes (see CHANGELOG)
The gridPtr method is no longer publicly available. All grid
methds can bee called through a reference to the grid obtained
by the grid() method. The parameter method for dgf parameters
is now accessible through GridCreator::parameters(...).



git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@15314 2fb0f335-1f38-0410-981e-8018bf24f1b0