(cherry picked from commit 2a1a4b5a)

Philippe 14/01/2021: IO: add IO_Field_write_nc4_N4, IO_Field_partial_write_nc4_N2, IO_Field_partial_write_nc4_N3 and IO_Field_partial_write_nc4_N4 subroutines

Philippe 08/01/2021: allow output files with empty variable list (useful if IO_Field_user_write is not empty)

This is incomplete for the moment. MesoNH must always be compiled with this key for the time being.

Philippe 06/01/2021: IO: add coordinates for dimension variables in diachronic files (not all yet done)

Philippe 17/12/2020: Write_time_coord: generalize to vector of dates and add management of date intervals (conform to CF conventions)

Philippe 07/12/2020: add support for partial write of fields (optional argument: koffset, not all subroutines, no LFI spport)

Philippe 07/12/2020: add CLEANLIST1D_ll subroutine + use it to correctly deallocate associated memory

(cherry picked from commit 2646cee7)

Philippe 07/12/2020: add CLEANLIST1D_ll subroutine + use it to correctly deallocate associated memory

(cherry picked from commit 2646cee7)

Philippe 07/12/2020: add CLEANLIST1D_ll subroutine + use it to correctly deallocate associated memory

Philippe 07/12/2020: IO: add support for Z-split files in IO_Field_partial_write_nc4_X2 + create IO_Select_split_file subroutine

Philippe 26/11/2020: IO: remove dead code (compatibility of dates with old MNH, not working anymore)

Philippe 24/11/2020: rename NMNHDIM_BUDGET_MASK_TIME -> NMNHDIM_BUDGET_TIME and time_mask -> time_budget

Philippe 13/11/2020: IO: improve CF compliance (add missing unit, does not write empty standard_name)