Manipulate files in working sets from plugins

[Dmitry Risenberg]

Hi all!

While trying to fix this bug
https://bugs.kde.org/show_bug.cgi?id=260663 I found out that the
plugins have no access to working sets API. In this particular case,
the Patch Review plugin has to call IDocument::close to remove
document views from review area, thus also removing corresponding
documents from working sets in other areas. A quick fix to that can be
saving those other working sets and loading them back after the review
has finished, but I think a better option would be to add an interface
to ICore for access to working sets and also provide an API to
manipulate working sets contents (something like
WorkingSet::setFileList). Any objections/comments on this?

-- 
Dmitry Risenberg