Support for medium and low tile levels in the OSM Vector Map of Marble

As of now Marble supports rendering of OpenStreetMap vector data for higher tile levels. In order to make the vector OSM theme complete and end - user ready, support for medium and lower tile levels must be added.

For supporting low level rendering( levels 1, 3, 5, 7, 9), Marble should render using the Natural Earth vector dataset instead of the OSM vector dataset. The reason for this is that Natural Earth dataset has categorically arranged data which is required for step by step rendering of lower levels. Apart from this the rendered data should be styled so as to match the OSM theme and tiling support must be added on the server and client side.

For the medium level tiles, rendering must be performed using the OSM dataset. OSM dataset gives us many small chunks and nodes for a particular geographic data item. These chunks and nodes need to be filtered and reduced to a manageable size for each specific level so as to get optimal performance and less screen clutter.

Rendering of higher level tiles can be improved by adding rendering support for roof-types and textures tags of buildings.