Draws its children in a continuous loop.
:duration - The number of milliseconds each child should be displayed (number)
[:animation
{:x 10, :y 10, :duration 200}
[:image {:name "player_walk1.png", :width 80, :height 80}]
[:image {:name "player_walk2.png", :width 80, :height 80}]
[:image {:name "player_walk3.png", :width 80, :height 80}]]