More improvements of the overview / basic map. The overview map is what you see when you zoom out (20 km and below, normal detail) or press ctrl-G in Mapsource  or Basecamp:

• It makes the rendering faster in Basecamp/ Mapsource
• size of the map tiles are reduced with 10%.
• lower zoomlevels of the OFM basic map are not longer visible on the GPS, so you will see the default basemap of the GPS earlier. This also improves the rendering speed.