Philippe 16/02/2021: bugfix: GMASK3D_RELAX was not computed if OHORELAX_UVWTH=F and needed by other variables

(cherry picked from commit aede627c644b55ea93cd6ff8d9c57bf93060bcbc)

(cherry picked from commit 18e800b5f0188048744a5c11fdcdab84d3eaeb83)

Philippe 12/02/2021: bugfix: change STATUS for opening files containing flash information (NEW->UNKNOWN)

Philippe 04/02/2021: budgets: bugfixes for LDRAGTREE if LIMA + small optimisations and verifications

(needed if LBU_KCP=T, LBU_ICP=F and LBU_JCP=F for CART budgets)

Philippe 15/01/2021: bugfix: SV_FLUX for flyers were not computed correctly and overwritten in files

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

-ZXCOEF and ZYCOEF were not computed if CVBALL
-PCIT was used if CCLOUD/=ICEx (not allocated)
-PSEA was always used even if not allocated (CSURF/=EXTE)
-do not use PMAP if cartesian domain