Rather than calling dbffileisnull or shpfileisnull. This should be
faster and more robust.

Remove component radius4 of derived type eddy and field radius4 of
`outermost_contour.dbf`. They are not used any longer.

The attribute written was always true.

We will need this new shapefile in program `eddy_graph` only for a non
longitude-latitude grid. We add a new dummy argument `grid_lon_lat` to
procedure `shpc_create` to decide whether we create the shapefile
`extr_proj`.

Reverting commit 8ef2473e. We no longer have preprocessor directives
since commit 2905904d.

Useful to read shapefiles from conversion of Matlab data.

It was confusing to mix opening an SHPC with broadcasting some part of
the resulting shpc variable.

Read `days_1950` and `eddy_index` from outermost and max-speed
shapefiles. When we only opened shapefiles in reading mode, we never
needed these fields. It was enough to read the date and eddy index
from the extremum shapefile. But when we open in appending mode, we
need all the fields.

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.

Thus remove too component interpolated of derived type eddy and
component `extr_interp` of derived type shpc.

We now impose that all eddies in an SHPC have the same
orientation. Remove field `extr_cycl` from the derived type shpc and
add field cyclone to shpc. When reading an eddy, give it the
orientation of its SHPC. Add argument cyclone to procedure
`shpc_create`. Create a file `orientation.txt` in each SHPC. When
writing an eddy, check that its orientation matches that of the SHPC.

Rename triplet to collection, `shp_tr` to shpc, shpt to shpc in
comments, identifiers and file names.

`read_eddy.f90`, `read_field_indices.f90` and `shp_tr_open.f90` will
become common to Overlap and `Inst_eddies` because they will be used
in `Inst_eddies/Tests/test_set_max_speed.f90`. So there are now enough
common files to justify a new directory.

Update required following commit 05dd4fc1.

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.

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

Use the components for field identifiers of a variable of type
`shp_triplet` instead of storing these field identifiers in variables
of modules `init_shapefiles_m` and `read_field_indices_m`. The dummy
argument hshp of procedure `read_field_indices` becomes
`intent(inout)`.

Create derived type `shp_triplet`. Motivation: we need to manipulate
two triplets of shapefiles in program `eddy_graph`. Use everywhere a
variable of type `shp_triplet` instead of the three variables
`hshp_extremum`, `hshp_outermost`, `hshp_max_speed` when all three of
them appear. Rename character variable `shp_triplet` to
`shp_triplet_dir`.

Prepare for a run of `test_get_snapshot` which receives a
snapshot. Generalize main unit `test_get_snapshot`: it is now
parallelized; it reads a date index from stdin; it sends a snapshot
from process 1 to process 0 if it is run with 2 processes.

The logic of the overlap program will be that all processes access the
triplet of input shapefiles. So modify subroutine
`read_field_indices`: process 0 reads field indices and broadcasts
them. This implies that programs `test_overlap`, `test_read_snapshot`
and `test_read_eddy` use MPI.

Generalize `algorithm.py`.

In program `test_send_recv`, read input SHP triplet from command line
instead of requiring it to be present in the current directory with
the name `SHP_triplet_old`. Generalize `test_send_recv`: read
`ishape_last` from file. In `test_send_recv`, all processes must now
access the triplet of shapefiles since process 0 reads field
indices. For the sake of uniformity, read and broadcast k1 from
process 0.

procedure so it can be used by program test_set_all_outerm.

Move dummy argument corner of set_all_outerm to last position.

Bug fix in procedure get_snapshot: urc(2) must always be lower than
nlat, even if periodic is true. Fix the same bug in procedure
set_all_outerm: llc(2) >= 1 and urc(2) <= nlat even if periodic is true.

Bug fix in procedure set_all_outerm: the lower bound of dummy argument
ssh is not always 1.

Make script examine_ssh_values.py work for a periodic domain.

Make program test_set_all_outerm work for a periodic
domain. max_radius is now chosen at run-time (we must change it for
a very coarse grid). Add a corresponding test.

In written shapefiles, replace field "area" by field "r_eq_area",
that is radius of disk of equal area. This is a smaller number so it
needs fewer characters, especially for a global coarse grid.

validity of an eddy depending not only on its amplitude but also its
surface. (Note that, in this version, the component valid is redundant: one
can simply test the component out_cont%n_points.)

hard-coding them.

Remove component twice of type eddy, no longer needed.