[Sirius][Sequence] Provide Gates and oblique Async Messages in Sequence Papyrus-Sirius diagrams

• Aynchronous messages supporting the constraint source.y ≤ target.y are oblique edges in the Sequence diagram.

• Only asynchronous messages can be oblique. Synchronous messages remain horizontal.

• Gates can be attached to CombinedFragment and InteractionUse as a border node

• Messages can be attached to Gates ** Gate as a source: *** Message Synchrones *** Message Asynchrones *** Message Reply *** Message Create *** Message Delete *** Message Lost ** Gate as a target: *** Message Synchrones *** Message Asynchrones *** Message Reply *** Message Found

• For Time Observation, Time Constraint, Duration Observation, Duration Constraint: ** a Duration Observation can have a Gate as source and target. ** a Duration Constraint can have a Gate as source and target. ** a Time Observation can have a Gate as source and target. ** a Time Constraint can have a Gate as source and target.

• Links (Comment and Constraint for the source) can have Gates as targets.