Break up positionMapAt() so that setUserPositionAt() can happen independently
Listen for user moving map, and don't recenter from GPS until they touch "Refresh"
Remove mMap.invalidate() calls
Merge pull request #726 from keverets/pan-mode

Pan mode
Add PathOverlay to the map, to draw the GPS track

Also, use a consistent color for the GPS dot and track.

Note that post OSMDroid-4.2, PathOverlay is deprecated, and OSMDroid
recommends using Polyline in the OSMBonusPack:

https://github.com/osmdroid/osmdroid/issues/40