My little turtle has become to draw colorful `HI!`

Updated Turtle Graphics with Shoes to v0.5.

# turtle_graphics_snapshot_colorful.png

Added pen_style method. This is Paul Harris's idea. He suggested me. Cool! B-)

pen_style :stroke => 'red', :strokewidth => 12

I could try to use method_missing. I guess this is a very good exercise for Ruby Metaprogramming. :-D

Thanks, Paul!
ashbb