Clean up code regarding track info, attached wpt and hidden flag.

Issue #456 resolved
kiozen created an issue

Clean up behaviour of hidden flag regarding attached waypoints and track info.

  • A track point with text in the desc field can never be hidden.
  • A track point with attached waypoint can never be hidden.
  • If a hidden track point is closer to a waypoint than a visible one it is set visible and the waypoint is attached.