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`.

I did not like the difference of treatment between corner and step.

Read `input_ssh_nml` before reading the NetCDF files. Preparing to
read from the namelist whether the grid is uniform.

Preparing to read a second input variable from stdin in procedure
`input_ssh`.

So that the program `eddy_graph` can read it, instead of deducing it
from the longitude coordinate.

Instead of deducing it from the longitude coordinate. The deduction
could not be generalized to a non-uniform longitude-latitude
grid. Also, the test on `step(1)` and nlon was not perfectly robust.

We are trying to simplify the logic in program `inst_eddies`. Also,
the program `inst_eddies` should not write `grid_nml.txt` to the top
level of the SHPC directory since several instances could run in
parallel for several slices. So we are leaving it as a task for a
script above `inst_eddies` to create `grid_nml.txt` at the top level
of the SHPC directory. In tests, we have to move `grid_nml.txt` to
SHPC because we use `SHPC/grid_nml.txt` in other tests.

Create `cropped.nc` and `unpacked.nc` in the current
directory. Several instances of script `inst_eddies.py` for different
slices should run in different directories.

We are reverting commit d4d05bc2. It was not true that we needed two
input fluxes in the Fortran program. `inst_eddies.py` can read the
file `config_nml.txt` and merge its content to stdin for the Fortran
program.

Always read coordinates from NetCDF file and create `grid_nml.txt`. Do
not try to read `grid_nml.txt`. Reverting part of commit c4410682. We
are trying to simplify the logic in program `inst_eddies`.

Add argument SHPC-dir to script `inst_eddies_Aviso.py`. We want to be
able to run `inst_eddies_Aviso` in parallel for several slices. Since
we write `used_config_nml.txt` to the current directory, we need to
run the parallel instances from different directories. So the current
directory cannot always be the directory containing the SHPC to be
appended to.

Add argument `SHPC_dir` to function `loop_inst_eddies`. We want to be
able to run `loop_inst_eddies` in parallel for several slices. Since
we write `used_config_nml.txt` to the current directory, we need to
run the parallel instances from different directories. So the current
directory cannot always be the directory containing the SHPC to be
appended to.

We are trying to simplify the logic in program `inst_eddies`. Also,
the program `inst_eddies` should not write `used_config_nml.txt` to
the top level of the SHPC directory since several instances could run
in parallel for several slices. So we are leaving it as a task for a
script over `inst_eddies` to create `used_config_nml.txt` at the top
level of the SHPC directory.

Do not try to read `used_config_nml.txt`. We are reverting commit
d9a67386, trying to simplify the logic in program `inst_eddies`. We
consider that using a single configuration for several runs of
`inst_eddies` is the problem of a script over `inst_eddies`, not the
problem of `inst_eddies`. Drawback: we write again
`used_config_nml.txt` in several runs of `inst_eddies`, but this is
not important.

We want to be able to run `inst_eddies` from a directory other than
the directory containing the SHPC to be appended to. Preparing to
write `grid_nml.txt` and `used_config_nml.txt` in the current
directory. To be able to do this in parallel for several slices, we
need to be running in different directories.

Makes more sense.