message: Fix wrong capitalization of 'Plural forms:' label
diff: </object>
  <object class="sizeritem">
  <object class="wxStaticText" name="plural_forms_label">
  - <label>Plural Forms:</label>
  + <label>Plural forms:</label>
  </object>
  <flag>wxLEFT|wxRIGHT|wxBOTTOM|wxALIGN_RIGHT|wxALIGN_CENTER_VERTICAL</flag>
  <border>5d</border>
  