Summary:
This simplifies quite a bit the logic, we don't need to do the
bookkeeping ourselves anymore. Only missing would be a "isDirty" flag on
the settings object which explains the m_currentTheme member variable
which is still around to have something to compare against in
updateNeedsSave().

Reviewers: #plasma, mart

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D24394