Add a new flag, CHIMIE_INPUT_ALL that allow to start a simulation with mode=0, but reading all informations linked to the chimie. In other word, we can start from a file that contains info on the stars and gas metallicity or simply from an already evolved model (whithout using mode=2).

modifications in :
init.c : during initialisation of specific variables
io.c : in blockabsent

Error messages are also improved to ensure the
compatibilty between

1. the number of elements present in the header of an initial condition file header.flag_metals
2. the number of elements present in the chemical parameter file Cp->nelts

3. and the number of elements of NELEMENTS hardcoded in the code.

git-svn-id: https://svn.epfl.ch/svn/gasp@43 67b3a02f-582b-4e65-a7f6-2b87bd0cff7a