Generate interface IDs (IID) for Windows platforms

Although Delphi allows for interfaces without an assigned IID (or GUID), certain operations do indeed require a IID, such as SysUtils.Supports().

Hence, to support such "Delphi interface best practices" it would be extremely helpful if the generator could create a valid IID at least for Windows platforms (which is Delphi's natural target and development platform).

The code should be held easily expandable to support other platforms in the future.