validity of an eddy depending not only on its amplitude but also its
surface. (Note that, in this version, the component valid is redundant: one
can simply test the component out_cont%n_points.)

>= 0 everywhere outside of procedure local_extrema.

In test Nearby_extr, use output from Get_snapshot_region_1_noise since
we now use suff_amp in extremum shapefile.

than extr_map /= i.

Preparing to remove the coding of sufficient amplitude in extr_map: do
not use anywhere the sign of extr_map, use the component suff_amp of
the type eddy instead.

In program test_successive_overlap, I would rather not use default
values for namelist variables.

Add a larger test for successive_overlap, to have eddies wih
insufficient amplitude in the region.

title lines in "edgelist_1.csv". Add python script reading
"edgelist_1.csv" into a NetworkX graph.

GPC_F and GPC must be used.