* Move layout options to separate toolbar
* Enable stepping on quantities, remove special history curve stepping for now
* Allow stepping ensembles and cases
* Add step next/prev and add new sub plot
* Make sure the subplot selected in the tree is shown in the multiplot viewer.
* Clean up multiplot toolbar handling a bit
* Remove old summary plot toolbar.
* Create a specialized summary plot page for showing multi plots
* Make summary plots always show in grid of selected size.
* Allow dragging summary addresses into empty main window area
* Limit grid to 4x4 cells