Refactor update event and added state move

[kelindar]

This pull request changes the tile update event structure, as it also adds an ability to Move() a state of a tile from one to another via a new Move() method on a Tile[T] itself. This moves the state and notifies observers correctly (and only once) by dispatching an event with both New and Old tiles set, their location, and the state which was added/deleted. To accomplish this I needed to refactor a bunch of stuff as well.

Enhancements to Observer Notification System:

• Introduced UpdateState struct to encapsulate the state of a tile before and after an update. (view.go)
• Modified pubsub to include Notify1 and Notify2 methods for handling notifications for single and multiple observers respectively. (view.go) [1] [2]

Improvements to Tile Update Mechanics:

• Refactored writeTile, mergeTile, addObject, and delObject methods to use UpdateState for more granular update notifications. (grid.go) [1] [2]
• Added Move method to Tile struct to handle moving objects between tiles and notify observers accordingly. (grid.go)