Implementation of the NPROMICRO mechanism in the LPACK_MICRO=F case

[SebastienRietteMTO]

In mode_ice4_pack, we can compute the microphysics on a selection of points by packing them in new arrays before calling ice4_stepping (LPACK_MICRO=T) or call directly ice4_stepping on all the points (LPACK_MICRO=F).

With the packing, we can activate the NPROMICRO mechanism; but this mechanism is not available without the packing.

This issue describes how to implement NPROMICRO without packing:

• add variables for lower and upper bounds of the DO loops used in the different processes
• these variables will evaluate to 1 and KSIZE in the packing case (to reproduce the present computation)
• without the packing, these variables will target a moving slice, with a DO loop around the call to ice4_stepping