Avoid temporary file creation by KML plugin
The KML file can be directly extracted into a QByteArray, no need to create temporary files/directories.
This indirectly also fixes the marble thumbnailer for KML and KMZ files. It uses a geodata_cast<GeoDataDocument>, which fails for a KMLDocument. Removing the temporary files allows to just use a GeoDataDocument.
Edited by Stefan Brüns