Marble: Visualize data aging (tiles)

completed by: goffrie

mentors: Torsten Rahn

"Marble usually downloads the map data in the form of texture tiles. These tiles get downloaded incrementally whenever a certain area of is viewed at a certain zoom level. As soon as each tile has been downloaded it starts to age: after some time the tile expiration time has passed. Once this happens and once the tile is supposed to get displayed the tile is downloaded again to allow for an update of the tile. For debugging purposes it would be nice to display the age of the tile encoded in color shades. This can be easily done using the blending framework.
Expected results: tiles show color tints that represent the age of a tile
Prerequisites: Knowledge of Qt and C++"