NPEFix doesn't find patches outside class files

[andre15silva]

NPEFix isn't able to produce textual patches for NPE's that could be fixed with changes in files outside of the class files in which the error occurs.

This is can be exemplified by https://github.com/andre15silva/failingProject/tree/npefix-scope, where changes to nopol_example_12.NopolExamplePackageFile.java or nopol_example_12.NopolExampleStackFile.java could fix the respective error, but only textual patches for nopol_example_12.NopolExample.java are produced.

This behavior can be found in eclipse-repairnator/repairnator#1172 (comment), where the scope option influences what files are passed to NPEFix.