Memory Card Game (High Score Board Issue #10) (By: @YunSuk)

Moderator: @CommanderHamster
~requested: 360

#10 
Added scoring system and high score board gui.

Includes:
Scoring System
Label that tells current score 
Button that shows high score board 
Updated the instruction
Extra warnings for restarting the game (restart resets the points) 
Updating ability of High Score Board
Pop-up that asks if user want to save the score (if it is a high score)
Frame that asks user's name (only first 20 characters are read)
Closing the window when the game is finished and high score is shown, so user cannot touch the finished game

*solved merge conflict