* use metric horizontal coordinates in the transformed plane when available
* write vertical coordinates (SLEVE not yet done)

Philippe 15/01/2018: IO: write horizontal dimensions in NC4 files: improvements + problem corrections

Philippe 12/01/2018: IO: add ZTOP field for model top (useful for mesh description in CF convention)

* HDF5 1.8.9 -> 1.8.20
* netCDF 4.1.3 -> 4.5.0
* netCDF-fortran 4.1.3 -> 4.4.4
* added libaec 0.3.2 (equivalent to szlib but without licence problems)

+ use them

* FD_ll removed several fields not used anymore
* removed GETFD_COMM function
* bug corrections: use NLFIFLU instead of NLU
* bug correction in CLOSE_ll: .NOT. GPARALLELIO => GPARALLELIO

+ treated correctly NOPEN_CURRENT and NCLOSE fields for Z-splitted files

+ simplified IO_FILE_READ/WRITE_NC4_xy calls
+ added IO_FILE_WRITE_CHECK subroutine