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.

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

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.

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.

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 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.

Do not always specify uv-file when it is the same as ssh-file.

So we do not call `time.perf_counter()` a second time after a simple
assignment.

Preparing for a check on the first file.

Preparing for another call to this function.

Clearer and simpler. Also it avoids appending to a previous
`timings.txt` file.

Create `cropped.nc` and `unpacked.nc` in the slice directory, so that
several processes running `inst_eddies.py` for different slices can
run in parallel.

Instead of symbolic links. We want to avoid creating symbolic links
above SHPC because we want to run several instances of `inst_eddies`
in parallel.

So that several processes running `inst_eddies.py` for different
slices can run in parallel.

So we can print the error message from NCO, which is in standard
output. This is particularly useful when the longitude range specified
by xmin, xmax is not valid.

Changing my mind. In an SHPC, store shapefiles in
"Slice_{slice}/{orientation}" instead of
"{orientation}/Slice_{slice}". Two reasons: easier to store accessory
files from running `inst_eddies`, such as `perf_report` and output
from Torque submission script; clearer that a slice should contain the
same dates for both orientations.

Assume that a slice is in a directory
"{shpc_dir}/{orientation}/Slice_{slice}" where shpc_dir can be any
name, orientation is "Anticyclones" or "Cyclones" and slice is an
integer. Do not read or create any longer a file "orientation.txt" in
the slice directory. Add procedure `get_slice_dir`. Add dummy
arguments cyclone and slice to procedure `shpc_open`. Add dummy
argument slice to procedure `shpc_create`.

Rename `main_nml` to `config_nml` in module `config_m`.

In pandas for example, a column header name containing a blank is not
convenient.