tuned source structure;

eliminated patch: imitate jEdit.gotoMarker more directly;

tuned;

tuned signature: proper private vars;

tuned signature;

unused;

suppress NavigatorPlugin and its dependencies -- requires to update jedit component;

prefer search bar (with navigation buttons) over old-fashioned tool bar -- requires to update jedit component;

add navigation buttons to search bar, depending on property "navigate-toolbar" -- requires to update jedit component;

remove goto_buffer in favour of uniform goto_file;