Create intermediary variable `assoc_eddies`

Preparing for more complex association criterium.

Overlap/overlap.f90

@@ -39,6 +39,7 @@ contains
     integer i2 ! eddy index of successor
     integer l, n_select
     type(polyline) polyline_1, polyline_2
+    logical assoc_eddies ! association between eddies
 
     integer, allocatable:: selection(:)
     ! identifying numbers of a selection of extrema
@@ -96,7 +97,10 @@ contains
                    + floor((e1%extr%coord(1) - e2%extr%coord(1)) / twopi &
                    + 0.5) * twopi
 
-              if (inters_lines(polyline_1, polyline_2, min_inters_speed)) then
+              assoc_eddies = inters_lines(polyline_1, polyline_2, &
+                   min_inters_speed)
+
+              if (assoc_eddies) then
                  write(unit_edge, fmt = *) (k - delta) * e_overestim + i1, &
                       k * e_overestim + i2
                  e1%delta_out = min(e1%delta_out, delta)