Added option to single-expand any Win7 style item

Expands the "display as a list of drives" option from This PC to work on
almost any item in the Windows 7 style. Incompatible items have a new
setting called ITEM_NODRIVES which blocks the option from appearing.
This PC still uses the original "list of drives" text, while other items
use "list of links" instead. Sorting has been updated to account for
this option by adding a property called bFolderLink which marks any
folder, even if it is not explicitly expandable.

Src/StartMenu/StartMenuDLL/CustomMenu.h

@@ -15,6 +15,7 @@ struct CStdCommand7
 		ITEM_SINGLE=1, // this item never has sub-menu
 		ITEM_FOLDER=2, // this item always has sub-menu
 		ITEM_COMPUTER=4, // this item can be expanded only one level
+		ITEM_NODRIVES=8, // this item can never be expanded only one level
 	};
 	const wchar_t *command;
 	int nameID;