It was not convenient to read them with input function or on the
command line: too much to read this way, and not clear when saved in
JSON text file. And we already had to create a namelist file
anyway. And this way the namelists can be extended transparently.

Pass a namelist object instead of a string to functions
`loop_inst_eddies` and `process_1_file`. Preparing to integrate the
date and the slice to this object.

Read `inst_eddies_nml.txt` out of function
`loop_inst_eddies`. Preparing to modify the date in the namelist in
`inst_eddies_Aviso.py`.

Instead of `config_nml.txt`. Preparing to include other namelists in
this file.

Bug fix: do not provide standard input for `inst_eddies_Aviso.py`, it
does not read it.

In the case of non-uniform longitude-latitude grid: we read the whole
coordinate arrays from the NetCDF file; we have a different way of
inverting the projection, in `invert_proj`; the program `eddy_graph`
does not use `corner_whole` and step, which are not defined, it uses
instead the shapefile `extr_proj`.

In `extr_map.nc`.

Preparing for a non-uniform longitude latitude grid.

For a non-uniform longitude-latitude grid. As in `input_ssh` for
`max_radius(1)`. See commit 803b9bcc.

Preparing to make dummy arguments longitude and latitude optional.

Rename variable `corner` of module `read_grid_m` to `corner_whole`. As
in module `input_ssh_m`. Cf. commit ef43e372.

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

Of derived type `shpc_slice_handler`.

Since it is already written to a shapefile.

Always write shapefile `extr_proj` in procedure
`save_snapshot`. `save_snapshot` is only used in tests. In these
tests, `read_snapshot` is called so `extr_proj` is computed. We want
to check as much as possible with `save_snapshot`.

Rather than the value of `s%list(1)%extr%coord_proj(1)`.

Preparing to generalize to a non-uniform longitude-latitude grid.

Invert order of dummy arguments of procedure `read_grid`.

In program `test_mean_speed`. To make it work with a non-uniform grid,
we would have to read a contour in projection coordinates.

Use `uniform_lon_lat` from modules `input_ssh_m` or `read_grid_m` to
compute actual argument of `shpc_create`.

In program `test_read_eddy`.

In program `examine_eddy`.

Replace dummy argument `grid_lon_lat` of procedure `shpc_create` by
`with_proj`.

Specify whether to read shapefile `extr_proj` in procedure `shpc_open`
instead of just trying to read this shapefile. Use `uniform_lon_lat`
to decide whether to read the shapefile. As `shpc_open` is called in
both programs `inst_eddies` and `eddy_graph`, we cannot access
variable `uniform_lon_lat` of module `input_ssh_m`, which is not used
in program `eddy_graph`, nor variable `uniform_lon_lat` of module
`read_grid_m`, which is not used in program `inst_eddies`. So we add a
dummy argument `with_proj` to procedure `shpc_open`.

In module `input_ssh_m`. Read it from `input_ssh_nml`.

Rename variable `corner` of module `input_ssh_m` to `corner_whole`.