Core: Fix several coverity issues:

* CID 350582: Big parameter passed by value
* CID 350639: Big parameter passed by value
* CID 305234: Uncaught exception
* CID 316529: Uncaught exception
* CID 350597: Uncaught exception
* CID 350623: Uncaught exception
* CID 332690: Uncaught exception
* CID 332700: Unchecked return value
* CID 350576: Uninitialized scalar field
* CID 350587: Uninitialized scalar variable
* CID 192606: Uninitialized scalar field
* CID 332699: Uninitialized pointer field
* CID 350561: Dereference null return value
* CID 350610: Dereference null return value
* CID 350567: Dereference after null check

src/Gui/TaskView/TaskDialogPython.h

@@ -104,7 +104,10 @@ public:
     virtual bool reject();
     /// is called by the framework if the user press the help button 
     virtual void helpRequested();
-    
+
+private:
+    void clearForm();
+
 private:
     Py::Object dlg;
 };