Merge arome rain_ice with:
- Ryad's versio: optimisation, KPROMA blocs
- Meso-NH version: subgrid precipiation
Arome aux:
- mode_ll to provide get_indice_ll
- mode_budget

Known issues:
- Bug around KPROMA blocs: results are different when used
- precipitation fraction cannot be used as long as condensation is not merged
- mode_ice4_sedimentation_momentum is still not plugged

Modifications prepared by Ryad are stored in arome/modset_Ryad
To help the merging of ice4_fast_ri, the array syntax was replaced
by a DO loop