Gui: Use getObject<T>() helpers in classes

This commit is generated using regex based find and replace:

```
s/[\w:]+_cast\s*<([^>]+)\*>\s*\(\s*getObject\(\s*\)\)/getObject<$1>/
s/[\w:]+_cast\s*<([^>]+)\*>\s*\(\s*([^)]*)\s*->\s*getObject\(\s*\)\)/$2->getObject<$1>()/
```

To regenerate if needed.

src/Mod/Surface/Gui/TaskFilling.cpp

@@ -72,7 +72,7 @@ bool ViewProviderFilling::setEdit(int ModNum)
         // object unsets and sets its edit mode without closing
         // the task panel
 
-        Surface::Filling* obj = static_cast<Surface::Filling*>(this->getObject());
+        Surface::Filling* obj = this->getObject<Surface::Filling>();
 
         Gui::TaskView::TaskDialog* dlg = Gui::Control().activeDialog();