Improve crossing point calculation

[Joerg Ewald]

Right now crossing points are calculated on the actual UTM cylinder. These points are then marked on the map. This is wrong for two reasons:

1. We should use WGS84
2. The crossing often happens as a crossing into the tolerance zone. In that case we should mark the point on the tolerance line, not the closest point on the actual cylinder.

To fix 2., change crossing point coordinates calculation to use the corresponding tolerance cylinder (inner or outer), using the current algorithm. This should already improve the results sufficiently. If not, also change the calculation from UTM to WGS84 (e.g. using the direct method for the used WGS84 distance calculation algorithm).