new feature: simulated duplex edges using parallel edges. - head arrow takes first color, tail arrow takes second color
new feature: simulated duplex edges using parallel edges.
- head arrow takes first color, tail arrow takes second color

BMJHayward/graphviz,jho1965us/graphviz,jho1965us/graphviz,pixelglow/graphviz,kbrock/graphviz,jho1965us/graphviz,jho1965us/graphviz,MjAbuz/graphviz,jho1965us/graphviz,BMJHayward/graphviz,BMJHayward/graphviz,MjAbuz/graphviz,ellson/graphviz,tkelman/graphviz,tkelman/graphviz,ellson/graphviz,BMJHayward/graphviz,kbrock/graphviz,kbrock/graphviz,tkelman/graphviz,ellson/graphviz,jho1965us/graphviz,kbrock/graphviz,BMJHayward/graphviz,pixelglow/graphviz,kbrock/graphviz,BMJHayward/graphviz,BMJHayward/graphviz,tkelman/graphviz,tkelman/graphviz,ellson/graphviz,tkelman/graphviz,BMJHayward/graphviz,MjAbuz/graphviz,pixelglow/graphviz,MjAbuz/graphviz,pixelglow/graphviz,jho1965us/graphviz,pixelglow/graphviz,kbrock/graphviz,tkelman/graphviz,MjAbuz/graphviz,tkelman/graphviz,MjAbuz/graphviz,jho1965us/graphviz,ellson/graphviz,BMJHayward/graphviz,kbrock/graphviz,pixelglow/graphviz,jho1965us/graphviz,ellson/graphviz,jho1965us/graphviz,BMJHayward/graphviz,kbrock/graphviz,pixelglow/graphviz,pixelglow/graphviz,kbrock/graphviz,MjAbuz/graphviz,pixelglow/graphviz,MjAbuz/graphviz,ellson/graphviz,tkelman/graphviz,BMJHayward/graphviz,ellson/graphviz,MjAbuz/graphviz,kbrock/graphviz,kbrock/graphviz,ellson/graphviz,pixelglow/graphviz,MjAbuz/graphviz,tkelman/graphviz,jho1965us/graphviz,MjAbuz/graphviz,pixelglow/graphviz,ellson/graphviz,tkelman/graphviz,ellson/graphviz