Implement support for the gx:Tour KML element and some (not yet all) of its sub elements:

• Add a GeoDataTour class which inherits GeoDataFeature and has getters/setters for identifier
• Add a kml handler for gx:Tour. See KmlTrackTagHandler as an example of how to deal with the gx: namespace. Have it extract the identifier attribute. Handle the parent element in the same way as KmlPlacemarkTagHandler.cpp does (i.e. append itself to parents that are containers)
• Add a TestTour.cpp test to the test suite. Have it test the parsing similar to TestScreenOverlay.cpp

References:

• https://developers.google.com/kml/documentation/kmlreference#gxtour
• http://marble.kde.org/kml-guide.php