Add 'reset' button to reset canvas to player's previous configuration

[brylie]

When the player configures the canvas and clicks 'run', there is no easy way to go back to the configured state. This may be important, as the player could want to tweak the positioning of elements, etc.

Task

• Determine how to store canvas configuration in memory
  • initial level setup (static)
  • player piece configuration (changeable)
• create data structure in game element to keep track of level configuration(s)
• when player adds piece to canvas, update data structure
• after running the attempt, either immediately reset the level or allow player to click a button to reset