NoDisplay interpretation

[Mark McLoughlin]

Hi,
	I've just added a test to menu-spec which interprets NoDisplay=true as
follows:

  - in a .desktop file, it makes that entry basically not exist

  - in a .directory file its the same behaviour as a <Deleted> in the 
    <Menu> node

	Shout if its being interpreted differently somewhere else.

Cheers,
Mark.