Reimplement PRRV plugin

[koppor]

The PRRV plugin seems to be useful to visualize relationships across papers. It should be integrated or it should be documented, why it is not integrated. Refs JabRef#152

This ticket tracks the current state of affairs.

As graphical rendering, the LGPL licensed library G is used. Version 1.0 has been released on December 2009 without any updates until now. Maybe, JavaFX can be used for that? (Refs #38, where we discuss charting libraries)

The plugin relies on the paper titles. All white spaces are removed from the references. For each paper: check references of other papers. Iff title string (with whitespaces removed) is contained there, there is a relation ship. (See ReferenceRelationshipViewDialog.java, line 258)

Update Reimplement the plugin functionality based on modern technology.

Steps:

1. Rely on stored connections in JabRef (maybe need to be defined) - first idea: cites
2. Derive connections from PDF

[oscargus]

I don't like the reference list nor the graph in the PRRV-plugin. There are better graph drawing frameworks and as discussed in #14 there may be other formats to keep relations between entries. On the other hand, the automatic linking of PRRV seems quite useful.

[koppor]

Besides the plugins discussed at #38, I like prefuse very much.

[oscargus]

I think JGraphT https://github.com/jgrapht/jgrapht with JGraphX https://github.com/jgraph/jgraphx is also worth considering.

[koppor]

Superseeded by JabRef#7160