give the cache file a header and check that it's valid when reading from the cache
give the cache file a header and check that it's valid when reading from the cache

svn path=/trunk/KDE/kdelibs/phonon/; revision=738469

sandsmark/phonon-visualization-gsoc,sandsmark/phonon-visualization-gsoc,sandsmark/phonon-visualization-gsoc,sandsmark/phonon-visualization-gsoc