[Language idea] move `color` for the turtle drawing to a higher level

[OnnoEbbens]

A few months ago the color command was added to the drawing with turtle. I really like that students can now use colors! However I think we should introduce this command in a higher level (3 or 4) because the first level contains a lot of information already. Also it would be nice to use the color in more higher level adventures since it is now only shown in level 1 and not mentioned in any higher level (although it does work in higher levels).