Motivation: we want to call `open_shpc` and `read_field_indices` from
program `inst_eddies` without making it an MPI program for one process only.

Because we are going to add preprocessor directives.

Change path from `Overlap/Analysis` to Analysis, following commit
3e41a613.

The program `test_write_overlap` was removed in commit c440ce20.

I added assert in commit 83123e30, I do not know why, it was not used.

`test_nearby_extr` does not need NetCDF since commit 83123e30.

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.

Remove `shpc_create` from use list in main program `test_overlap`. It
is no longer needed since commit 50d2f596.

Remove `shpc_create.f90` from source files of target `eddy_graph`. It
is no longer needed since commit 50d2f596.

Update to commit cb25161 from cmake repository.

Add test for existence of target `NetCDF_Fortran::NetCDF_Fortran`. If
the target already exists, because `find_package(NetCDF_Fortran)` has
already been called then we cannot create again the target. This
happens if we are a sub-project of a project that first creates the
librairies.

In case we are a sub-project.

Assuming the englobing project builds the corresponding librairies.

The procedure does not exist any longer.

A node is no longer identified by date and eddy index.

One can manually add the key cyclones to the returned dictionary.

Replace `tests_old_dir` by PWD for tests in the same series.

Move content of `tests.json` to the end `Tests/short_tests.json`.

There were only three files in `Overlap/Analysis`.

There are other files in `Overlap/Tests/Input` with the same content as
removed files. The redundancy came from commit c58c21b7.

Add `node_id_param.json` to requirements of `report_graph.py`.

Since we now produce from Fortran edgelists with node indices, we use
`report_graph_int.py`.

Instead of filenames constructed from the orientation. So we need to
create symlinks before running the script. It is clearer this way that
the script processes a single orientation, and that the processing
does not depend on the orientation. The script does not take a command
line argument any longer.

Rename variable `N(anti|cyclo)` to `N_eddies` in file
`N(anti|cyclo).mat`. Motivation: allow more transparent processing in
`overlap_v6.py`.

Rename `edgelist_no_header.csv` to `edgelist_unsorted.csv`.