Update OsmDroid to 4.2

It has removed the "Safe" set of overlays, etc.
Move the clearing of cache to onDestroy() rather than onStop()

onStop() gets called too frequently for it to be wiping out caches.
Use GPS updates from service only, don't try to test MLS at the same time
Jump directly to the point if this is the first fix, otherwise animate over
Save zoom level on rotation
Save center of the map and restore when rotating
Merge pull request #686 from keverets/osmdroid-fixes

MapActivity fixes