Put initialization of GPS broadcast reception in onStart()

It's removed in onStop() so should be initiated in onStart().
Without this change, if the user left the map and came back, they
would no longer get GPS updates.
Use the service's last location if available and the center hasn't been set in other ways
Update Hindi translation
Update Marathi translation
Merge pull request #734 from vinitraje/master

Update Hindi & Marathi translations (@vinitraje)
Merge pull request #730 from keverets/avoid-ocean

Use the service's last location if available and the center hasn't been set in other ways
Merge pull request #725 from keverets/map-resume

Put initialization of GPS broadcast reception in onStart()
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