Simple DAS Trainer v1.3

The purpose of this modification to NES Tetris is to assist learning the DAS (Delayed Auto Shift) method of playing. An unfavourable DAS charge value (0-9) is visualized by changing the color of the background from dark gray to something else:
* During entry delay: red
* Pressing `left` or `right` just after entry delay: yellow
* All other times: bright gray

The original statistics have been replaced. The topmost number is now total piece count since game start. The remaining numbers represent how many pieces each color has appeared for, shown as the percentage of total piece count.

Pressing `select` during play turns on visualization of *all* DAS charge values during entry delay, using blue for 10-15 and green for 16.