Support character-spacing tag in markup

How to apply it in TextEditor:

    textEditor.SetProperty(Dali::Toolkit::TextEditor::Property::TEXT,
                           "Hello <char-spacing value='-3.0f'>Hello </char-spacing>"
                           "<char-spacing value='3.0f'>Hello </char-spacing>"
                           "<char-spacing value='-6.0f'>Hello </char-spacing>"
                           "<char-spacing value='6.0f'>Hello </char-spacing>"
                           "<char-spacing value='0.0f'>Hello </char-spacing>");
    textEditor.SetProperty(Dali::Toolkit::TextEditor::Property::ENABLE_MARKUP, true);

Change-Id: Ic24b6cd7e0b88fba175fdc008345956a8fa7980f