View with custom state, iteration

[kelindar]

This pull request introduces significant changes to the Grid and View functionality, including the introduction of a new Observer interface and the refactoring of the View structure to support state and type parameters. The most important changes are outlined below:

Refactoring and New Functionality:

• view.go: Introduced a new Observer interface and refactored the View structure to support state and type parameters. The NewView function now creates a view with a given state, and the Resize, MoveTo, MoveBy, MoveAt, Each, At, WriteAt, MergeAt, and Close methods have been updated to use the new structure. [1] [2] [3] [4] [5] [6] [7]

Observer Handling:

• grid.go: Removed the View method from the Grid structure and added the Observers method to the Tile structure to iterate over all views observing a tile. [1] [2]

Utility Functions:

• point.go: Added pack and unpackRect methods to the Rect structure for packing and unpacking rectangle representations.

Documentation Update:

• README.md: Updated the documentation to reflect the changes from View to NewView and provided additional information on the type parameters for the NewView function.