Improve AR paths

[kylecorry31]

• [x] Use the geographic AR point instead, and figure out how to pin it to 2m below the user in a way that looks good
• [ ] Show label on path when focused (path name)
• [ ] Show direction of path (arrows)
• [ ] Re-add path view distance (after optimizing performance)
• [x] After calculating path snapping, apply offset rather than calculating paths again
• [ ] Improve path snapping when GPS changes (it currently jumps around)
• [ ] Improve performance (better algorithmic complexity, reduce calculations required, only update when required)
• [ ] Factor in path elevation (current position = user elevation - 2, other positions = user elevation - 2 - current point elevation)
• [ ] Adjust snapping distance based on GPS accuracy
• [x] Experiment with showing markers on the path or tapering it (to help estimate distance)