Remove more wxT() macros from samples

Also use wxString instead of wxChar* strings.

Closes https://github.com/wxWidgets/wxWidgets/pull/950

samples/internat/internat.cpp

@@ -397,8 +397,8 @@ void MyFrame::OnPlay(wxCommandEvent& WXUNUSED(event))
     }
     else if ( num == 9 )
     {
-        // this message is not translated (not in catalog) because we used wxT()
-        // and not _() around it
+        // this message is not translated (not in catalog) because we
+        // did not put _() around it
         str = "You've found a bug in this program!";
     }
     else if ( num == 17 )