Move instructions around

Preparing for the new structure. Note that the code is
degraded (temporarily) because the definition of `polyline_1` is
repeated uselessly inside the loop on `l`.

Overlap/overlap.f90

@@ -72,14 +72,6 @@ contains
 
          n_select = size(selection)
 
-         if (n_select /= 0) then
-            if (e1%speed_cont%n_points /= 0) then
-               polyline_1 = e1%speed_cont%polyline
-            else
-               polyline_1 = e1%out_cont%polyline
-            end if
-         end if
-
          DO l = 1, n_select
             i2 = selection(l)
             associate (e2 => flow(j)%list(i2))
@@ -87,6 +79,12 @@ contains
               ! delta}
               delta_long = e1%extr%coord(1) - e2%extr%coord(1)
 
+              if (e1%speed_cont%n_points /= 0) then
+                 polyline_1 = e1%speed_cont%polyline
+              else
+                 polyline_1 = e1%out_cont%polyline
+              end if
+
               if (e2%speed_cont%n_points /= 0) then
                  polyline_2 = copy_shift(e2%speed_cont%polyline, delta_long)
               else