DUE: Fri, Oct 24th

Create a typing tutorial program.

Have a welcome message for the program.

The program will display a random letter on the screen and the
person must press the correct letter. Let the preson keep pressing
the letters until they get the correct letter.

Make a beep if they press the wrong letter!

Once they press the correct letter, then display a congratulations 
message.
The person is able to press the ESC key to exit.

Write a function called, next_letter that will indicate what the next 
letter is. Have it return the letter.

Write a function called check_letter that will check to see if the 
person entered the correct letter. The program will keep having the
person entering letters, until the correct one is entered. If they press 
an ESC key return from the function. The check_letter function will
return the last letter entered. This way your program can see if the
person pressed the ESC key.

Write a function called 

Use a do-while loop, since the person must press at least one letter.
Exit the loop when the letter they press is equal to the ESC key's 
value.

system("cls");
This will clear the screen.