Added inverse-exponential relationship between simonColors.length and hightlightTimer and waitTimer.

- Added DECAY_CONST, minHighlightInterval, and minWaitInterval to be used in the function dictating the intervals.
- Said function was added to simonWait() and simonDisplay() to reduce the time things are displayed for as the game goes on, making it more exciting and harder.
- Added DEBUG_WAIT_INTERVAL and DEBUG_HIGHLIGHT_INTERVAL.