clarified defaults;

tuned signature;

clarified tree row handling;

tuned;

tuned;

cell-specific row height based on its font, e.g. relevant for DPI scaling on Windows;

clarified module name;

--HG--
rename : src/Tools/Graphview/visualizer.scala => src/Tools/Graphview/graphview.scala

always swap panels, which leads to slightly better GUI layout;

tuned;

proper tooltips -- override action toolTip which is empty here;

discontinued attempt at alphabetic_order -- selection via regex should be sufficient;

proper selection of nodes via regular expression;

suppress some controls that don't work yet;

proper scrolling wrt. transform;
tuned signature;

clarified main actions and keyboard focus;

tuned signature;

support for tree view on graph nodes;
misc tuning;