Rename file `test_write_eddy.f90` to `test_write_null.f90`. The name
was badly chosen because the program is not a unit test of procedure
`write_eddy`. In fact, it does not even call `write_eddy`.

Update `CMakeLists.txt` files to take into account commit 3289c070.

We can build some test sequential programs under Overlap.

Directory Tests was created in commit 40a1c5aa.

Useful for ARM Performance Reports and Intel Application Performance Snapshot.

It was difficult to find the `CMakeLists.txt` that controlled the the
compilation of a given file from the message of a compilation error.

Since `NR_util` has been integrated into Jumble.

Instead of copying files from the cmake repositoty.

Rather than with Unix-specific chmod command. This requires CMake `3.20`.

The programs in this project do not depend directly on them. If they
are secondary dependencies, it is the responsibilty of the primary
dependencies to find them.

Only three files were left in cmake, not enough to justify a directory.

Change of philosophy. We do not force the choice of compiler options
from the project, we leave them to the user at configuration. We just
need to display a warning for the option `-ffpe-trap=invalid`.

Move the call to `find_package` for EZMPI to
`Overlap/CMakeLists.txt`. We are reverting in part commit f04aea8b
since `test_set_max_speed` no longer uses MPI.

Note that programs `test_max_speed_contour_ssh` and `test_weight`
depend on fortranGIS through the module derived_types. Compilation
worked without linking to fortranGIS because objects used by
`test_max_speed_contour_ssh` and `test_weight` in
derived types do not use fortranGIS.

Following commit e741203 of `GPC_F`. We have to add this
`find_package` of GPC in `Detection_eddies` because `GPC_F` now
declares a dependency on the abstract target GPC.

Assuming the englobing project builds the corresponding librairies.

Use higher level procedures in main program
`test_set_max_speed`. Allows to read easily more information: cyclone,
`ssh_extremum`, `coord_extr` from the shapefiles. So we do not ask
this information to the user. The drawback is that we have to call
MPI (because of `read_field_indices`) even if we do not really use
it. We move the calls to `find_package` for EZMPI and `GPC_F` to the
top-level `CMakeLists.txt` since these libraries are now necessary in
both `Inst_eddies` and Overlap.

Create and use module FindNetCDF_Fortran, modeling on FindNetCDF.

Move Fortran source files used in tests of both parts, `Inst_eddies`
and Overlap, to directory Tests at root of repository.

Also split the tests, Fortran source files, Python files and JSon
files. Keep at the top level the files used in both `Inst_eddies` and
Overlap.

Motivations for the split:

- The top directory contained many files.

- It may be useful to compile only one of the two sub-projects. For
example, only `Inst_eddies` on Ciclad, where MPI 3 is not available.

To avoid inadvertant modification of `eddy_graph.sh` instead of
`eddy_graph_in.sh`.

Motivation: we are going to split the edge list file into two files.

`unit_edgelist` was just transmitted by procedure overlap from main
program unit to `write_overlap`. So now overlap does not see
`unit_edgelist`. Further motivation: we are going to split the edge
list file into two files.

Missing libraries in `target_link_libraries`. This appears now because
some links are now declared private in the libraries.

Replace script `mkdir_nproc.sh` by script
`eddy_graph.sh`. `eddy_graph.sh` is a wrapper script for program
`eddy_graph`. It includes the creation of output directories that was
done by `mkdir_nproc.sh`. `mkdir_nproc.sh` was only used for program
`eddy_graph`. There was the need to automate the concatenation of
output files for a run with several MPI processes.

Add a test for `eddy_graph`.

Improve the handling of the NetCDF Fortran library in cmake files.
Add the configuration of `eddy_graph_in.sh`.

In main program `eddy_graph`, do not write title lines in files
`unit_number_eddies` and `unit_edgelist` because these files are
concatenated for all the MPI processes by `eddy_graph.sh`. So the
title lines are added by `eddy_graph.sh`.

Add main program `eddy_graph`.

Change order of dummy arguments of `dispatch_snapshot` and overlap.

Rename files and identifiers: change `"shp_triplet"` to `"shp_tr"`.