modified:   chapter_03/1_zoog_as_dynamic_sketch.rb
	modified:   chapter_03/4_drawing_a_continuous_line.rb
	modified:   chapter_03/5_mouse_pressed_and_key_pressed.rb
	modified:   chapter_03/6_interactive_zoog.rb
	modified:   chapter_05/08_square_following_edge.rb
	modified:   chapter_07/02_calling_a_function.rb
	modified:   chapter_13/02_random_number_distribution.rb

various changes