Update label allocation tracking numbers after swapping

Negate any label that was swapped out and set any newly swapped in to zero.

Labels that were swapped out and back in again do not change their order.

Updates #76

lib/Biodiverse/Randomise.pm

@@ -1697,7 +1697,30 @@ END_PROGRESS_TEXT
     #  we used to have a memory leak somewhere, but this doesn't hurt anyway.    
     $cloned_bd = undef;
 
-    if ($track_label_allocation_order) {   
+    if ($track_label_allocation_order) {
+        #  negate any swapped out labels and set any swapped in labels to 0
+        no autovivification;
+        my $sp = $sp_to_track_label_allocation_order;  #  shorthand
+        EL:
+        foreach my $el ($sp->get_element_list) {
+            my $list_ref   = $sp->get_list_ref(
+                list => 'ALLOCATION_ORDER',
+                element => $el,
+            );
+            my $label_hash = $bd->get_labels_in_group_as_hash_aa($el);
+            my %combined = (%$list_ref, %$label_hash);
+            next EL if scalar (keys %combined) == scalar (keys %$list_ref)
+                    && scalar (keys %combined) == scalar (keys %$label_hash); 
+            foreach my $label (keys %combined) {
+                if (exists $list_ref->{$label} && !exists $label_hash->{$label}) {
+                    $list_ref->{$label} *= -1;  #  negate - we were swapped out
+                }
+                elsif (!exists $list_ref->{$label} && exists $label_hash->{$label}) {
+                    $list_ref->{$label} = 0;    #  set to zero
+                }
+            }
+        }
+        #  now add it to the basedata
         $new_bd->add_spatial_output (
             name => 'sp_to_track_allocations',
             object => $sp_to_track_label_allocation_order,