Provide capability to perform diff / merge

[Aurelien-Pin]

When having a Python script importing data in a Capella model, it would be nice to:

• perform a copy of the Capella model at the beginning
• perform the modifications on the copy of the Capella model
• perform a diff / merge between the original model and the modified copy

This will allow user to review and validate the modifications performed by his Python script before really modifying the Capella model