Re-factored due to Rubocop.
Width and Height are now calculated based on components.
Added game_over?

It returns whether the stack has reached to top, which is Game Over.
Added checks for game over.
Re-factored lower levels to use GridPoint / Point
Point / GridPoint used throughout shapes
block map and shapes communicate via GridPoint

Blockmap#add, #at, and #empty and Shape#blocks deal in GridPoints.
Pausing and Game over windows classified