MPI-AMRVAC setup code and parameter files for the Kelvin-Helmholtz linear
growth rate test from Vandenbroucke & De Rijcke.

The code should be configured using
$AMRVAC_DIR/setup.pl -d=22 -g=16,16 -p=hd -eos=gamma -phi=0 -z=0

The naming convention is as follows:
 - gr_c100_hllc: 100x100 finite volume simulation
 - gr_c200_hllc: 200x200 finite volume simulation
 - gr_c400_hllc: 400x400 finite volume simulation