a11y: Tab through sprites to read how many are in the puzzle

[philschatz]

For non-sighted users it would be useful to get an overview of what is in the puzzle.

One way to do that is to use the Tab key to cycle through different sprites in the puzzle. When cycling, it would be nice to hear the sprite name, the number of occurrences, and the locations. For example:

1. Pressing Tab would output "Player (1) at 3:2"
2. Pressing Tab would output "Target (1) at 4:5"
3. Pressing Tab would output "DirtyDishes (1) at 3:3"
4. Pressing Tab would output "Wall (18) at 1:1-5, 2:1-5, 3:1,4,5, 5:1-5"