Create commands to execute movements

[Ludocius]

The next commands will allow the turtle to do its behaviors

Command Meaning

• 1 Pen up (it doesn't let the mark slip by)
• 2 Pen down (it does a mark)
• 3 Turn right.
• 4 Turn left.
• 5,10 Move forward 10 spaces (replace 10 for a different number).
• 6 Display the 20-by-20 array.
• 9 End of data (sentinel).

[Ludocius]

Implementation added: https://github.com/Ludocius/Turtlemovements/pull/13