Preserve pin numbering when duplicating

We renumber duplicated pins but the previous order was essentially
random.  This keeps the numeric order of the pins on the screen, falling
back to position if they are not numbered

eeschema/tools/symbol_editor_edit_tool.cpp

@@ -894,11 +894,42 @@ int SYMBOL_EDITOR_EDIT_TOOL::Duplicate( const TOOL_EVENT& aEvent )
 
     commit.Modify( symbol, m_frame->GetScreen() );
 
-    EDA_ITEMS newItems;
+    std::vector<EDA_ITEM*> oldItems;
+    std::vector<EDA_ITEM*> newItems;
 
-    for( unsigned ii = 0; ii < selection.GetSize(); ++ii )
+    std::copy( selection.begin(), selection.end(), std::back_inserter( oldItems ) );
+    std::sort( oldItems.begin(), oldItems.end(), []( EDA_ITEM* a, EDA_ITEM* b )
     {
-        SCH_ITEM* oldItem = static_cast<SCH_ITEM*>( selection.GetItem( ii ) );
+        int cmp;
+
+        if( a->Type() != b->Type() )
+            return a->Type() < b->Type();
+
+        // Create the new pins in the same order as the old pins
+        if( a->Type() == SCH_PIN_T )
+        {
+            const wxString& aNum = static_cast<SCH_PIN*>( a )->GetNumber();
+            const wxString& bNum = static_cast<SCH_PIN*>( b )->GetNumber();
+
+            cmp = StrNumCmp( aNum, bNum );
+
+            // If the pin numbers are not numeric, then just number them by their position
+            // on the screen.
+            if( aNum.IsNumber() && bNum.IsNumber() && cmp != 0 )
+                return cmp < 0;
+        }
+
+        cmp = LexicographicalCompare( a->GetPosition(), b->GetPosition() );
+
+        if( cmp != 0 )
+            return cmp < 0;
+
+        return a->m_Uuid < b->m_Uuid;
+    } );
+
+    for( EDA_ITEM* item : oldItems )
+    {
+        SCH_ITEM* oldItem = static_cast<SCH_ITEM*>( item );
         SCH_ITEM* newItem = oldItem->Duplicate();
 
         if( newItem->Type() == SCH_PIN_T )