introduce WidgetMoverButton (to realize the "move layer" feature in the upcoming layer oriented sample editor)

Add the possibility to show the empty widget in ItemComboWidget also for other items (e.g. running jobs)

Add a blank widget to ItemComboWidget for the case that a nullptr SessionItem is set as the current item (instead of the show/hide logic)

Merge remaining funcionality of JobOutputDataWidget into JobResultsPresenter and delete obsolete JobOutputDataWidget

Remove ItemStackPresenter (which was only used in "single widget mode" anyway) from JobOutputDataWidget

introduce sample selection list (model & view) - the left pane of the new layer oriented sample editor

Get rid of message "DEBUG: bool QCPLayoutGrid::addElement(int, int, QCPLayoutElement*) There is already an element in the specified row/column: 0 1"

move item infos to item catalog (in the future the info will be used at different locations, not only the sample toolbox)

move example infos to example factory (in the future the info will be used at different locations, not only the sample toolbox)