Extend plot.sfnetwork to include the possibility of specifying different args for nodes and edges about sfnetworks

[agila5]

Another idea in this regard would be to copy the approach adopted by plot.igraph:

The first method is to supply named arguments to the plotting commands: plot.igraph, tkplot or rglplot. Parameters for vertices start with prefix ‘vertex.’, parameters for edges have prefix ‘edge.’, and global parameters have no prefix. Eg. the color of the vertices can be given via argument vertex.color, whereas edge.color sets the color of the edges. layout gives the layout of the graphs.