fix wxTextCtrl::Replace() under wxGTK; added unit test for it and describe its effect on the insertion point

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@57253 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/textentrycmn.cpp

@@ -73,6 +73,7 @@ void wxTextEntryBase::Replace(long from, long to, const wxString& value)
         Remove(from, to);
     }
 
+    SetInsertionPoint(from);
     WriteText(value);
 }