* panel-applet-frame.[ch]
Add action signal move-focus_out_of_panel to move focus from applet to
next or previous object on panel. Currently Tab and Shift+Tab are the
keys which do this.

* foobar-widget.[ch]
Add action signal focus_panel to support moving focus to the panel

* panel.c:
Remove unused argument PanelData specified for panel_event()
Set focus on panel if button release happens in panel and panel is
not focus widget.