Wait for the end of the execution of a cell

[HaudinFlorence]

Using an event synchronization primitive, wait that the execution of a cell is finished before to start the execution of the following one.

[davidbrochart]

You might want to rebase, to resolve conflicts.

[HaudinFlorence]

You might want to rebase, to resolve conflicts.

This has been done

[HaudinFlorence]

Thanks, I just tested it and it works fine! The busy indicator in JupyterLab even has the correct behavior, so I'm not sure anything else is required? Although it could be that JupyterLab only uses the shell messages, but in general we should make sure that the IOPub messages have the right status too,

Thanks for your review. The idea is to complete the implementation in the future with defining a status of all the kernels based on IOPub messages.