Autosaving and new puzzle menu added!

Puzzle Tiles now saves your puzzle every minute and when you close it. If it cant find a save upon opening, it loads a small default puzzle which functions as a tutorial. When you complete a puzzle you can now open a menu and set the width and height for your next puzzle.

Together these changes add a lot of functionality to Puzzle Tiles. It feels like a game now instead of a prototype. A very basic game with few options and only one puzzle image, but it's a game.