Fix edge drawing in fdp to allow other values for splines. The original code was written when there were only line segments and splines.
Fix edge drawing in fdp to allow other values for splines. The original code was written when there were only line segments and splines.

ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz