ISO19139 to ISO19115-3 / Add support for multilingual metadata records.

Add multilingual metadata support by converting gmd:locale to mdb:otherLocale and copying gmd:PT_FreeText and element attributes (eg. gco:nilReason, xsi:type) for gmd:CharacterString elements:

```
<gmd:title xsi:type="gmd:PT_FreeText_PropertyType">
  <gco:CharacterString>Template for Vector data in ISO19139 (multilingual)</gco:CharacterString>
  <gmd:PT_FreeText>
    <gmd:textGroup>
      <gmd:LocalisedCharacterString locale="#FRE">Modèle de données vectorielles en ISO19139 (multilingue)</gmd:LocalisedCharacterString>
```
is converted into
```
<cit:title xsi:type="lan:PT_FreeText_PropertyType">
  <gco:CharacterString>Template for Vector data in ISO19139 (multilingual)</gco:CharacterString>
  <lan:PT_FreeText>
    <lan:textGroup>
      <lan:LocalisedCharacterString locale="#FRE">Modèle de données vectorielles en ISO19139 (multilingue)</lan:LocalisedCharacterString>
```