Support all standard kml files

You may want make a larger bump to the version number if you merge this PR, as it potentially (not very likely) breaks KML files if they were generated very poorly and not in line with the KML standard:

https://developers.google.com/kml/documentation/kmlreference#coordinates

That said, this makes BorderPatrol more robust and less picky, so I really hope it gets merged.  Thank you for releasing this library!