Update issue 452.
Create and handle a ReusableBitmapDrawable and a BitmapPool which reuses tile Bitmaps rather than constantly reallocating new Bitmaps.
Cleaned up MyLocationNewOverlay and CompassOverlay. Removed passing redundant provider to enable() methods.
Reverted a few changes from the last commit and instead of making the setter public I just added parameterless enable() methods. Also added constructors that create default providers for the overlays.