Layout View: Grant a place of honor to the "Layout Algorithm" option

[spoenemann]

The option "Layout Algorithm" is the most important one and has a special meaning among all layout options. It should be put into a privileged place, e.g. a dedicated line above the property sheet that contains the other options.

[le-cds]

Yeah, why not. That line should of course only be visible (or at least only enabled) if a diagram element is selected that is a parent.