CBaseBarSite: Ask the CBaseBar to close itself when the x button is pressed.
CBaseBar: Hide the bar and inform its site that it is closing when it gets the close command.
CShellBrowser: Cache the guid of the current vertical bar and use it to report correct command status to the toolbar.
Also implement toggling the Folders, Favorites, History and search commands.
CInternetToolbar: Query the Folders and Search command status from the site so that they can be properly be shown as pressed.
