Qt Editor: Allow hotkey (F2) to duplicate selected objects.

Also reset cursor pos to center of duplicated objects to ensure they're on screen when duplicating by hotkey.

src/editor/C4ConsoleQtMainWindow.ui

@@ -993,6 +993,9 @@
    <property name="toolTip">
     <string comment="res">IDS_MNU_DUPLICATE</string>
    </property>
+   <property name="shortcut">
+    <string>F2</string>
+   </property>
   </action>
   <action name="actionEjectContents">
    <property name="text">

src/editor/C4ConsoleQtState.cpp

@@ -342,6 +342,9 @@ bool C4ConsoleQtMainWindow::HandleEditorKeyDown(QKeyEvent *event)
 	case Qt::Key_Delete:
 		::Console.EditCursor.Delete();
 		return true;
+	case Qt::Key_F2:
+		::Console.EditCursor.Duplicate();
+		return true;
 	}
 	uint32_t shift = 0;
 	if (event->modifiers() & Qt::AltModifier) shift |= MK_ALT;

src/editor/C4EditCursor.cpp

@@ -726,13 +726,25 @@ void C4EditCursor::PerformDuplication(int32_t *object_numbers, int32_t object_co
 		if (obj) obj->Call(PSF_EditCursorDeselection);
 	}
 	if (local_call) selection.clear();
+	int64_t X_all = 0, Y_all = 0, n_selected = 0;
 	for (C4Object *obj : ::Objects)
 		if (obj->Number > prev_oei)
 		{
 			obj->Call(PSF_EditCursorSelection);
-			if (local_call) selection.push_back(C4VObj(obj));
-			// TODO: Reset editor X/Y to center objects on cursor
+			if (local_call)
+			{
+				selection.push_back(C4VObj(obj));
+				X_all += obj->GetX();
+				Y_all += obj->GetY();
+				++n_selected;
+			}
 		}
+	// Reset EditCursor pos to center of duplicated objects, so they will be dragged along with the cursor
+	if (n_selected)
+	{
+		X = X_all / n_selected;
+		Y = Y_all / n_selected;
+	}
 	SetHold(true);
 	OnSelectionChanged();
 }