compute_updraft and compute_updraft_raha are OK
for compute_updraft_rhcj10: waiting for a answer from Rachel and/or Yves

+ compute_bl89_ml as a mode_

+ correction mf_turb_expl.F90

Replacement of modd_mfshall in AROME by modd_param_mfshall
Merge mf_turb_expl

OCND2 included in common code (from AROME version)
OCND2 specific code moved in common/micro or arome/dead_code directories
High/Low cloud included for condensation (from Méso-NH version)
Harmonie SPP code moved outside of physics
condensation and ice_adjust optimised by Ryad
compute_frac_ice as an elemental procedure

The 3 routines are merged into mode_compute_frac_ice
using optimisation (with pointers) developped by Ryad.

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

merge AROME, Meso-NH and Ryad's version
cleaning of forgotten modi
tools.f90 added from Meso-NH package

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

gradient* files are merged and moved in externals
shuman moved in externals
modification of arguments order for shuman and gradients

rename rmc01.f90 into rmc01.F90

- mv *.f90 *.F90
- bug corrections in bl89 and compute_bl89_ml
- code modification to take into account the new interface of
bl89 and compute_bl89_ml
- introduction of the REPRO48 compilation key

Creation of the temporary 'externals' directory for AROME.
This directory will contain the AROME specific version of
source codes that is not part of the PHYEX package but is
needed by the package.

Main mods:
- XRTM17, LOCEAN and ocean related constants added
- AROME specific version of modd_precision, modd_dynn created
- creation of a message system for AROME: modd_io and mode_msg

Other mods:
- mv budget in externals
- creation of the docs directory (containing working documents)
- creation of src/arome/gmkpack_ignored_files; the file contains
  the list of the source codes which must be ignored by gmkpack
  but was present in the main pack. This file is necessary while
  the ecboundle mechanism is not used.

Quentin 08/11/2021: MNH->AROME tridiag* (Philippe 18/04/2019: import small improvements from OPENACC branch)