Standardized all impact function population impact. (issue #910)
Raise an exception when adding a duplicate impact function name.
Merge pull request #1090 from cchristelis/develop

Standardized all impact function population needs. (issue #910)
Merge pull request #1092 from cchristelis/feature/handle_duplicate_class_names

handle duplicate class names
Pep8.
Merge pull request #1095 from ismailsunni/pep8

Pep8.

I will merge it since it's only small change and I want to make jenkins sunny again :)
Make test pass.
Merge remote-tracking branch 'origin/develop' into develop