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

# Conflicts:
#	src/LIB/SURCOUCHE/src/mode_scatter.f90
#	src/LIB/SURCOUCHE/src/mode_tools_ll.f90
#	src/LIB/SURCOUCHE/src/mode_toolsz_ll.f90
#	src/MNH/call_rttov11.f90
#	src/MNH/ch_f77.fx90
#	src/MNH/extend_grid_parameter_mnh.f90
#	src/MNH/ini_lesn.f90
#	src/MNH/latlon_to_xy.f90
#	src/MNH/ls_coupling.f90
#	src/MNH/radtr_satel.f90
#	src/MNH/rain_ice.f90
#	src/MNH/split_grid_parameter_mnh.f90
#	src/MNH/turb_ver.f90
#	src/MNH/write_lbn.f90

Revert "Quentin 11/12/2020: temporary force the possible uncorrected negative values to be > 0. This commit should be reverted soon and the missing right correction of negative values of rv must be found"

This reverts commit 582bf442.

-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

(cherry picked from commit d82def518a9d007cb8f8a827d7b872b774f4a965)

-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

(cherry picked from commit d82def518a9d007cb8f8a827d7b872b774f4a965)

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

Philippe 07/01/2021: IO: remove GCLOSE_OUT variable/dummy argument (lopened field of tpfile datatype can be used instead)