Changeset 5214 for LMDZ6/trunk/libf/misc

The fortran parameters file "iso_params_mod.F90" is introduced so that "tnat" and "alpha_ideal" are defined in a single place but used in several.
The "getKey" routine is only used in "infotrac" and "infotrac_phy" routines, but could be used outside this scope to get tracers parameters (read from "tracer.def") or isotopic parameters (read from "isotopes_params.def" - disabled for now).