Extensive check to find unused pachtes. In order to reduce flase positives it uses a whilelist to exclude them.

Data Format ( dev-libs/foo|foo-fix-1.12.patch|dev@gentoo.org:loper@foo.de ):
dev-libs/foo                                package category/name
foo-fix-1.12.patch                          patch which is not used by any ebuild
dev@gentoo.org:loper@foo.de                 maintainer(s), seperated by ':'