use test/tmp as temp dir for tests and make sure it's there

A freshly cloned NetLogo repo doesn't have a top level `tmp/` folder, so the extension tests requiring one were failing.
use most recent sbt launch script from 5.0.x branch
add tests for #86
separate allEdges/Neighbors from undirectedEdges/Neighbors - fix #86
preserve behavior of BreadthFirstSearch following fc7a997

Not entirely sure that is the right thing to do, though. Will open ticket.
add a first failing test for #85