A player has a hair color

[TheoPannetier]

Depends on

• Colors can be created #69

Before doing this issue, the issue above will need to besolved first!

// 68 A player has a hair color
    {
        player p;
        // A player's hair is black by default
        const color black; // tune the input as needed to get the right color
        assert(p.get_hair_color() == black);

        // Hair color can be set at construction
        const color red;
        p = player(red);
        assert(p.get_hair_color() == red);

        // Hair color can be set e.g. through options
        const color white;
        assert(p.get_hair_color() == white);
    }