Scripts, exhaustive solver, weighted competition

* New ECHO scripts
* Added exhaustive solver
* Refactored collecting satisfied and unsatisfied pairwise relations
into their own methods
* Refactored competition to directly add competing weights to the
propositional network instead of simply adding CONTRADICT links. Now
they work in the same way as joint explanations.
* TODO: move competition calculator into the Argument class
TODO: add Jung graph support
TODO: add ability to generate graph from ECHO arguments instead of
forcing user to go through GUI