We need ssh of extremum in `set_contours`, to compute `innermost_level_2`.

Because we are going to use it for another field.

Instead of standard output.

Since it is not in the shapefiles.

Remove option `--dashed` of script `plot_eddy_contours.py`. This
option was added in commit 5e0e0deb. The dummy argument dashed of
function snapshot is useful because we can call snapshot several times
on the same axes from elsewhere, but I do not see how the option
`--dashed` of script `plot_eddy_contours.py` is useful, since we
create a new figure when we run the script.

Check that `SHPC_dir` exists at initialization of instance of class
SHPC. Before this commit, if `SHPC_dir` did not exist, there was an
error trying to create `n_slices.txt`, which was less clear.

Add the possibility to write `cont_list` from `set_contours`. We want
to do that without impacting the main program unit `inst_eddies`. We
do not want to centralize variables at hight level in
`inst_eddies`. So we do not want to promote `cont_list` and `n_cont`
to dummy arguments of `set_contours`.

Split dummy argument `e` of `set_contours` into relevant components.
Motivation: make appear clearly input and output.

Split dummy argument `e` of `set_max_speed` into relevant components.
Motivation: make appear clearly input and output.

Replace dummy arguments `s` and `i` of procedure `set_contours` by
dummy argument `e`.

Move the computation of the search window for the outermost contour
and `outside_points` from procedure `set_contours` to main program
unit. The motivation is to have a clearer interface of procedure
`set_contours`, without `s` and `i`.

Rename module `set_all_contours_m` to `set_contours_m` and procedure
`set_all_contours` `set_contours`.

Rename file `set_all_contours.f90` to `set_contours.f90`.

Move the loop on eddies out of `set_all_contours`, up into the main
program unit. The motivation is to be able to easily study a
particular eddy, having access to `cont_list` and corresponding speed
values.

Bug fix: manage absence of a good contour within the outermost
contour.

Create a new figure in function `plot_distr_funct` if ax is None.

`config_nml` should be the same for `test_get_1_outerm` and
`test_set_max_speed`.