Fix for using https://github.com/nrbrook/TBXML.git rather than outdated TBXML repo.
Support for multiple consecutive LinearRings in a Polygon's innerBoundaryIs element

The form being:

<innerBoundaryIs>
  <LinearRing>
    <coordinates>...</cooordinates>
  </LinearRing>
  <LinearRing>
    <coordinates>...</coordinates>
  </LinearRing>
</innerBoundaryIs>