Account for node size in branch lengths

[dan-knight]

if (!nodes && length.from.node.edge) {
    tree <- adjust.branch.lengths(v,tree,node.radius, scale1);
    }

This does not always calculate accurate lengths for the second length column (when provided). I suspect it has to do with converting back from scaled (by scale1) units.

I removed this functionality temporarily until this is resolved. I also removed the nodes and length.from.node.edge parameters from SRCGrob, as they can be added back in without losing backwards compatibility.