Activation of the snow related modifications in AROME (work of Jean Wurtz)

[SebastienRietteMTO]

These modifications have not been introduced in the AROME version as they break the bit-reproducibility and, thus, need a more complex validation.
There are two solutions:

• rewrite the code to enable the bit-reproducibility
• validate the new results

Control to implement: when lred=F, lsnow must be F

Be careful, in arome, to keep consistency with ini_snow (easier if code is rewritten to enable bit-reproducibility)