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/PartDesign/Gui/ViewProviderMainPart.cpp

@@ -41,7 +41,7 @@ ViewProviderMainPart::~ViewProviderMainPart()
 std::vector<App::DocumentObject*> ViewProviderMainPart::claimChildren(void)const
 {
     std::vector<App::DocumentObject*> temp;
-    temp.push_back(static_cast<PartDesign::MainPart*>(getObject())->Sketch.getValue());
+    temp.push_back(getObject<PartDesign::MainPart>()->Sketch.getValue());
 
     return temp;
 }