D12002: Check if group < LastGroup, as KIconEffect doesn't handle UserGroup anyway

[Fabian Kosmale]

fabiank added reviewers: mart, dfaure, mlaurent.

REPOSITORY
  R302 KIconThemes

REVISION DETAIL
  https://phabricator.kde.org/D12002

To: fabiank, mart, dfaure, mlaurent
Cc: #frameworks, michaelh, ngraham, bruns