Have unique IfcGloballyUniqueId within the model suite

[thbeu]

The set IFC object identifiers are not unique within the model suite (since the files are likely manually crafted). It would be preferable if these identifers are unique such that importing applications can handle more than one IFC file simultaneously.

[Andrej730]

Sounds like it's an issue with the importing application that it cannot handle overlapping guids from loaded models - since it is possible that user would load multiple versions of the same model e.g. to investigate the changes.