Create properties in `cost_function.py` rather than in
`segments.py`. We do not use these properties in `segments.py`.

The property in the input edgelist is not the non-local cost function.

This test requires a specially prepared file `segmented.gt`:

```
head -n 100000 /data/guez/Oceanic_eddies/Global_1993_2020/Eddy_graph_anti/edgelist.csv >edgelist.csv
~/Detection_eddies/segments.py edgelist.csv segmented.gt
```

because we need input with `%Y/SHPC_(anti|cyclo)` arborescence for the
test.

Simply printing g displays the address of the graph, which may change
between runs. This was not convenient for the comparison of runs.

Motivation: being able to choose a different output format at
run-time. We use the graphml format for the automated test, because
graphml is a text format, so we can compare the results of two runs.

To be able to read edgelists output by the Fortran program.

They had the default values.

Remove unused `e_overestim`, `d_init`, `orientation`.

Use `comp_ishape` and `open_shpc` from `util_eddies`.

Do not store in memory all the records from shapefile
`max_speed_contour`.

But we should find some way not to impose a directory structure to the
user.

We do not want hard-coded paths in the script.

We do not want to change the script to change orientation.