Separate "activice" into latent heat release + radiative transfert

[jnaar]

The flag "activice" is used when we want to investigate the radiative effect of water-ice clouds. When true, we take ice particles in consideration when computing the radiative transfert. However, we also use this flag to account for latent heat release in cloud microphysics, which is a different physical process. We could want to investigate those two separately and thus call the latent heat release of clouds with another flag.