displayName should be element, not attribute.

[bengtmartensson]

Should be a child element instead of an attribute, multiplicity: *. Should take an xml:lang attribute (with unique-restriction), thus supporting multiiple languages.

In the same vein, adding a helpText element (that can be used for tooltips etc) would be a good idea, same xml:language handling and restriction.

Added 2021-04-12: For compatibility, the attribute form should still be accepted (though deprecated), and equivalent to a displayName element with xml:lang="en".

Added 2021-04-15: This defines a new version of the schema, which we will call 1.2 and will have the schema location systemID http://www.harctoolbox.org/schemas/girr_ns-1.2.xsd

Replaces bengtmartensson/IrScrutinizer#163

[bengtmartensson]

Although sensible, there is no application, present or planned for the near future, that takes advantage of the multi-language displayNames. So reschedule this to an indeterminate future.

Some preliminary work checked in into the branch displayNameAsElement.