Allow Qualifier attribute on Annotation elements within an Annotations element that does NOT specify a Qualifier attribute

Currently the Qualifier attribute is only allowed for Annotation elements that are "inlined" within their target model element, and forbidden when nested within an Annotations element.

While this makes some sense for qualifier values like UI.Device.Slate and UI.Device.Phone, it makes less sense for qualifiers like VCard.Type.Work and VCard.Type.Home. Separating these into several Annotations elements that targets the same model element makes getting the full picture actually harder.