ScoreBoard and GameEngine tweaks.

Tweaked Add() method of ScoreBoard– now adds all best scores (0
mistakes) unconditionally.
GameEngine now uses ScoreBoard’s CheckScoreIsHighscore() method (removed
bug where only one record was added in the ScoreBoard and no consecutive
if they were not better no matter the number of records in scoreboard).
Scoreboard now is shown even if you did not enter in it.
Renamed MaxScoresCount to NormalScoresToStore in ScoreBoard.