2010-07-06  Andreas J. Guelzow <aguelzow@pyrshep.ca>

	* src/gui-util.h (GnumericPopupMenuElement): add field
	* src/gui-util.c (gnumeric_create_popup_menu): handle new field
	* src/sheet-control-gui.c (context_menu_handler): handle removal
	  and cretion of comments
	(scg_context_menu): add new items for comment addition and removal