Fix for single-layer composites with < 1.0 opacity
Made selection more better and less buggy
Removed unused, dead SQLite code
Added lovely icons for adding/removing tilesources
Updated MapQuest sat URL to new one

as per http://developer.mapquest.com/web/products/open/map
Added ability to add tile sources from the GUI.

I probably need to make sure now that duplicate tile sources won't step
on eachothers' toes
Made sure that OSMTileSource has caching enabled by default