Add CloudKit to Core Data

[waldo]

As all relations are now unordered must now:

• Set position / ordinal fields.
• Compare position / ordinal fields when retreiving.

For example: player names and team names. Round score for position should probably change to score for team.

[waldo]

Add progressive migrations. Split migration into two parts. First one is custom and adds the position / ordinal fields and sets them while we still have the order from the ordered relationship. Second removes the ordered relationship.