Since `shpc_open` is called by all processes, reading d0 and
`ishape_last` in `shpc_open` implies that we do not broadcast d0 and
`ishape_last`.

Since processes need d0 to allocate `ishape_last`.

Store `ishape_last` and first date in components of derived type
shpc. We then remove arguments `d_init` and `ishape_last` of procedures
`read_snapshot` and `get_snapshot`.

Preparing for components `ishape_last` and `d_init` of type shpc.

Preparing for the case of several input SHPC.

We have to be consistent with function `adjust_n` in the same script.

`read_field_indices` is now called from `shpc_open` so the comment
no longer makes sense.

It was confusing to mix opening an SHPC with broadcasting some part of
the resulting shpc variable.

Rather than with Unix-specific chmod command.

Following convention for the source of `configure_file`. See Scott
2021 k1077, § 19.7.

Corresponding to the Fortran node index.

In procedure `get_snapshot`.

Note that we then have to declare `d_init` before `ishape_last` in
procedure `get_snapshot`.

Before reading `ishape_last`, because we are going to use `d_init` as
lower bound of `ishape_last`.

The correct syntax to sort on field 1 is `--key=1,1`. `--key=1` used
as key from field 1 to the end of the line. So the key was non-numeric.

By explicit formatting.

We are reverting commit e48b7f7e. I think I did not really appreciate
then that the number of days since 1950-1-1 is another date index. It
is clearer to use just one date index, which is in the dbf files. So,
in effect, we replace everywhere the old 0-based date index k by `k -
d_init`. Note that we no longer need argument `d_init` for procedure
`dispatch_snapshot` and we no longer need to write `d_init` to file
`node_id_param.json`. Note also that the value of every node index
changes by the amount `d_init * e_overestim`.

To search those names more easily.

Instead of referring to an external file.

Update dbf files with field date instead of `days_1950`.

We need this since `inst_eddies_Aviso.py` imports `inst_eddies` which
is in the binary directory.

Instead of copying files from the cmake repositoty.

When reading an eddy.

Rather than with Unix-specific chmod command. This requires CMake `3.20`.

Following convention for the source of `configure_file`. See Scott
2021 k1077, § 19.7.

Use a symbolic link instead of appending to `sys.path`. THe motivation
is that in the Python interpreter, the following statements failed
before the present commit:

```python
import sys
sys.path.append("/path/to/Detection_eddies/Inst_eddies/Analysis")
import plot_eddy_contours
```

`sys.path[0]` then does not contain
`/path/to/Detection_eddies/Inst_eddies/Analysis` so
`plot_eddy_contours` could not find `util_eddies`.

When there are more than 3 input files. We recover the convenience of
commit b34b85a8, with the underlying generality of commit d365e754.