Merge branch 'wxQt-memory-leaks' of https://github.com/catalinr/wxWidgets

Fix many memory leaks in wxQt port.

See https://github.com/wxWidgets/wxWidgets/pull/1243

samples/minimal/minimal.cpp

@@ -170,6 +170,7 @@ MyFrame::MyFrame(const wxString& title)
     wxButton* aboutBtn = new wxButton(this, wxID_ANY, "About...");
     aboutBtn->Bind(wxEVT_BUTTON, &MyFrame::OnAbout, this);
     sizer->Add(aboutBtn, wxSizerFlags().Center());
+    SetSizer(sizer);
 #endif // wxUSE_MENUS/!wxUSE_MENUS
 
 #if wxUSE_STATUSBAR