(instead of date_index = 1). This is the value read from the NetCDF
files. We have to increase the width of field date_index to 5 digits
(4 digits would only allow approximately 30 years since 1950).

In procedure read_snapshot, check that all input eddies have the same
date index, and return it as an additional argument.

Assume that the input NetCDF files contain a single date.

In program test_set_all_outerm, do not write file
"isolated_nodes_1.csv". Since s is defined by set_all_outerm only, all
the eddies are necessarily isolated.

order to take missing value attribute into account.

input NetCDF files rather than selecting a window. Clearer and easier
to set up new tests.

values at longitude boundaries, in case of periodicity.

Add argument "periodic" to procedures get_snapshot and
set_all_outerm. Duplicate values at longitude boundaries in ssh, u, v
if periodic. set_all_outerm can now call local_extrema with periodic
true. In procedure set_all_outerm, we shift the longitudes of outside
points if necessary.

In program test_get_snapshot, define periodic from step and nlon.

test_good_contour has more general input.

test_inside tests only inside, no loop on radius.

input depending on noise_around. So it is clearer to compute radius
outside of max_speed_contour_ssh. Thus, we simplify
max_speed_contour_ssh. radius is an input argument. The case where
radius == 1 must now be processed also outside of
max_speed_contour_ssh.

call only one procedure per test, and read all the required
data. (Also: there was much duplication of code between
test_set_outermost_contour and test_max_speed_contour_ssh.)

threshold. outermost_contour becomes set_outermost_contour. get_eddy
disappears: it will be absorbed in get_snapshot. get_snapshot is
temporarily broken so we do not compile test_get_snapshot.

set_outermost_contour is in charge of finding nearby_extr and the
initial value of level_try (get_outermost_contour was not). The method
for this depends on the value of noise_around. The rest of the
processing in set_outermost_contour is identical to what was done in
get_outermost_contour.

Made test_max_speed_contour_ssh more general: longitude-latitude
window and eddy identifying number may be chosen at run-time. Made
test_set_outermost_contour more general than test_outermost_contour
was: longitude-latitude window and eddy identifying number may be
chosen at run-time.

For both test_max_speed_contour_ssh and test_set_outermost_contour,
only the chosen longitude-latitude window is read from the NetCDF
files. We have to call local_extrema because set_outermost_contour
takes extr_map as an input argument (get_outermost_contour did not)
and because longitude-latitude window and eddy identifying number may
be chosen at run-time.