calculate distance with one known point

[tedder]

First, apologies because I'm not equipped to test this, nor am I sure it's correct, but I hope it's close.

The idea is to create a helper method for gps.location.distanceBetween(). That way the object's location can be used instead of needing to pass it back in:

gps.distanceBetween(otherLat, otherLng, gps.location.lat(), gps.location.lng())

Here's the helper method:

gps.location.distanceBetween(otherLat, otherLng)