(gui) Add a custom command to perform update on all diagrams
(XdfResource) Now use the default EMF fragments generator

Useful when diagram is serialized with links to network objects
(updater) Improve error management
(gui) In layout feature, correctly detect network ports
(gui) Add doc on "Update all diagrams" command
(gui) Remove useless specific cases for invalid connections
(gui) Remove useless INVALIDATED_REFINEMENT constant

Invalid refinement is detected when refinement URI is unresolvable
Merge branch 'net_serialization_updates'
Update current version to 2.1.0