The code has been updated in order to take into account correctly the variable HubbleParam, for star formation, cooling, chimie. This has been tested.

We also reintroduce the variable
#define FEH_SOLAR 0.0018
as it is used if the cooling use the metallicity but
the chime is disabled.
This was the origin of a bug.

git-svn-id: https://svn.epfl.ch/svn/gasp@23 67b3a02f-582b-4e65-a7f6-2b87bd0cff7a