ADDED: task 9.2.19, shows paths containing .forward that is a nonempty regular file
Works in check and modify modes, but it never modifies anything, thus added new tag: check-only
ADDED: task 9.2.18, shows paths containing .netrc that is a nonempty regular file
Works in check and modify modes, but it never modifies anything
ADDED: 9.2.17 Check for duplicate Group Names.
Works in check and modify modes, but it does not modify anything
ADDED: 9.2.16 Check for Duplicate User Names
Works in both check and modify modes, but it does not modify anything
ADDED: 9.2.15 Check for Duplicate GIDs
Works in both check and modify modes, but it does not modify anything
Merge pull request #2 from marcinpohl/MPsection9

First batch of Section 9