Fix typo
Remove TileSourceFactory.FIETS_OVERLAY_NL layer

This improves loading speed significantly
Set aTileSizePixels to 256

This fixes many 'java.lang.IllegalArgumentException: Problem decoding into
existing bitmap'.
MapBox returns 256x256 PNG tiles regardless of this parameter.
Use http:// instead of https:// Mapbox URL's

This speeds up tiles loading and fixes exception of strict mode: 'Explicit termination method 'close' not called'.
Disable hardware acceleration for MapActibity
OSMDroid does not support hardware acceleration yet
Clear tile cache when the activity is stopped
Reduce zoom levels range
Remove unused code
Add AccuracyCircleOverlay to map only once when the activity is created
Merge pull request #255 from illarionov/mapFixes0

Map improvements