don't display hidden variables in workspace view * symbol-information.h (symbol_information::Scope): Delete hidden. New field, unknown. Change all uses. * workspace-model.cc (workspace_model::workspace_model): Don't add "Hidden" tree_item to the top-level item list. (workspace_model::event_accepted): Don't delete 3rd item from top_level_item list. Don't add hidden items to the list. * workspace-view.h, workspace-view.cc (workspace_view::_explicit_collapse): Delete hidden. Change all uses.