parallelstream must not do an addAll to an ArrayList: it causes null entries

[udatny]

JCSG/src/main/java/eu/mihosoft/jcsg/Edge.java

Line 609 in 5801d91

edges.addAll(pEdges);

https://stackoverflow.com/questions/39093178/java-8-parallelstream-fill-arraylist

[miho]

Thanks for spotting this. There are probably a couple of other problematic locations.