Removed the separate migration info class and will instead focus on letting ball node implement NSCoding.
Revert "Removed the separate migration info class and will instead focus on letting ball node implement NSCoding."

This reverts commit 353a3928c988ca4cf01518b6c76a6feb4046dc39.
Started implementing a much slimmer migration info for the ball. Sending is performed, no receiving yet.
Removed the test-sending functionality between peers.
Added a public multiPlayerMode property on playScene.
Ball migration is successfully sent to the other peer.
Dropping ball from top in the opponent.
Added a ballInitiator property to find out which peer has the ball first.
Changed the path of paddle node into using a compact version of CGPath where a rectangle is created directly
instead of move to followed by add rect. Seems to be working as expected.
Change all rectangle shaped shape nodes to use a rectangle that is properly centered and
adjusted their position to fit the limits of the scene.
Added test code for testing the non-ball-initiator side during first migration.
Using the terms ball sender and ball receiver instead of initiator (which has no good opponent word).
For test purposes: Only send the ball straight up and down.
Added state handling for ball sender ball receiver.
Added a state enum called PPGameState which should be updated by both peers in a multiplayer game.
For a single player game, the state should be active all the time.
Refactoring.
Added checks of allowed game state changes.
Going from Active to Passive also allowed if the other peer starts the game.
Created a class that handles messaging with the other peer.
Removed unnecessary inclusion of multi peer manager.
Refactoring contact checking.