Default comparators for Positions

[buehlefs]

There are no default comparators for positions.
Positions are often sorted before they can be used in a TaskVerifier.
It would be beneficial to provide one or more comparator to be used by the TaskVerifiers.

[Vogel612]

Comparator.comparing(Position::getX).thenComparing(Position::getY) seems quite... workable to me

[buehlefs]

I will leave this issue open for now as this should be added to the documentation of Position.
This would make this option more visible expecially for java newcomers (and someone who does not know much about the Comparator package from java like me...)