D10742: get rid of the raw KFileItem pointers in KCoreDirListerCache

[Jaime Torres Amate]

jtamate added a dependency: D13211: Enable comparing KFileItems by url.

REPOSITORY
  R241 KIO

REVISION DETAIL
  https://phabricator.kde.org/D10742

To: jtamate, #frameworks, dfaure
Cc: bruns, kde-frameworks-devel, mwolff, markg, michaelh, ngraham