Because `$tests_old_dir/Extraction_eddies_region_5/SHPC` is opened
with `SHPC_class` in test `Plot_eddy_contours_window`, which will
create `n_slices.txt`, so there will always be this file only in
`$tests_old_dir/Extraction_eddies_region_5/SHPC`.

This is going to be simpler. Also, we will spare main memory when we
have a list of contours for each eddy, if we do not have a list for
invalid eddies.

Use test `Region_5_15_days` instead of outside experiment `Inst_eddies_4`.

We import in the test infrastructure the experiment `Inst_eddies_4`
because we want to no longer keep invalid contours, so we will need to
update the experiment.

Only define and print `n_radius4` and `n_missing_speed` if `with_radius_4`.

We cannot test `"radius4" in shape_rec_outer.record`, as
`shape_rec_outer.record` is not a dictionary. We could test `"radius4"
in shape_rec_outer.record.as_dict()` but it is better to test outside
of the loop in the field names of the shapefile reader object. The bug
comes from commit 83a61016.

Add default initialization of component `coord_proj` of type
extremum. As the type of `coord_proj` is integer, there may not be a
compiler option to initialize it. We want to detect when it has not
been defined.

As `grid_lon_lat` may be false, we define `e%extr%coord_proj`.

I do not see why this was not done in commit 24b5b079.

This shortens the file `test_get_1_outerm.f90`.

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`.

Because we are going to use it also for another shapefile than extremum.

It seems simpler than putting it in `$large_input_dir`. I do not see a
drawback.

Use component with type extremum in derived type eddy, instead of
components `coord_extr` and `ssh_extr`. Component `coord_proj` of
derived type extremum also replaces component `ind_extr` of derived
type snapshot.

For easier comparison of runs.

Add component `innermost_level` to derived type eddy. So
`innermost_level` does not transit as an argument through main program
unit `inst_eddies` any longer.