Full functional version of Tetris game

All the basic features are implemented:

• Main Menu
• Pause with P
• Restart on game with R
• Game Over panel and go to Main Menu
• Add three background musics persisting on the whole session with circular playlist and random initialization
• System of Score and Level
• Highscore on session
• Next box for the next block-group

Need to be improved:

• GameOver logic is messy and sometimes the last block is missed or overleaped