Edge directions and merging citing' and cited-by'

[pesho-ivanov]

The two views (papers citing and cited by the seeds) can naturally be visualized together. Such a view will not only show more relevant information but will also simplify the user interaction by skipping the choice.

Any (or both) of these two approaches can be used to distinguish the citing from the cited by nodes:

1. Adding direction to the edges (which will also allow for clean semantics for non-seed dependence Pagination of title search results #17)
2. DAG'ifying the graph (as cycles are possible) and plotting it left-to-right or top-to-bottom.

[barney-walker]

I think option 2 is the more natural solution.

Related ticket: #31

[no-identd]

I agree with the DAGification as the better option, but I'd also like to add a note:
If you do end up adding directed edges of some form, there's UX research (I can dig up the citations IFF you insist.) showing that tapering edges (thick at the start, thin at the end) function as much better visual indicators of direction than arrows do.