So we can run only individual tests if we want.

Because we want to factorize what follows.

Edge list file is not necessarily in current directory since commit
c328203b.

So that corresponding dates are in a possible
order. `edgelist_Isic_2.csv` still has the same edges than
`edgelist_Isic_1.csv` in a different order. Note that we also have to
change `e_overestim`.

Following the  move of `extract_component.py`.

Move script `extract_component.py` from directory Trajectories to
directory Overlap. It does not deal with trajectories and it does not
need the input graph to be a graph a segments.

Downgrade `sort_ssh` from argument of procedure `complete_ssh` to
local variable. `sort_ssh` is not used any longer in procedure
`set_max_speed` since commit 4a64f87d.

Instead of using a submodule. See Scott (2023 k1077, § 39.6.2 "Sharing
CMake Modules And Commands"). The drawbacks are: the directory cmake
is duplicated in each build directory; configuration requires a
network connection. The advantages are: it is easier to download the
project without git; we can more easily package a release.

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

This is useful to find the shortest path between the beginning and the
end of a trajectory, or to create a histogram of the number of
trajectories per component.

Bug fix: correct sign of variation of Rossby number and radius. We
have to be consistent with the computation of `delta_ro_mean` and
`delta_r_mean`. `delta_ro_mean` and `delta_r_mean` were computed by
subtracting origin from tail.

It does not make sense here to assume an ellipsoid: the computation of
the distance with $\cos \phi \delta \lambda$ and $\delta \phi$ is a
rougher approximation than treating the Earth as a sphere.

We avoid multiple conversions to rad of the same value, in the loop on
edges, since a segment can be head or tail of several edges.

Move functions `node_to_date_eddy` and `date_eddy_to_node` from script
`report_graph.py` to script `util_eddies.py`. `util_eddies.py`
contains more basic functions, it only imports
shapefile. `report_graph.py` imports networkx. It was not convenient
nor meaningful to require networkx for scripts that use
`node_to_date_eddy` or `date_eddy_to_node`.

Useless: there is a symlink to `util_eddies.py` in directory Overlap
since commit 56ca8ea3.

Read orientation from `expanded_traj.json`.

Installation has been tested with CMake `3.27`. Adding the maximum
version rids us of a warning message concerning policy CMP0144.

This seems to be a little faster, even if we do not use out-degree for
all the nodes. For `Global_1993_2023/Graph_anti`, this commit reduces the time
to define `traj_prop` from 23 s to 20 s.

We know that we are going to need in-degree for every node of the
graph. For `Global_1993_2023/Graph_anti`, this commit reduces the time
to define `traj_prop` from 31 s to 25 s.