Handle async printing

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There is some stuff that happens async in SuperCollider (loading buffers, booting the server, Tdefs).
Currently there is no way to collect this information and display it somewhere - it even contradicts the jupyter idea to some extend, yet it still would be nice to have the same as a raw post window?

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Pexpect has async support - this is probably helpful here?

As Jupyter notebooks also allow to execute async python code it is also maybe worth taking a look at how they handle printing.

https://pexpect.readthedocs.io/en/stable/api/replwrap.html#pexpect.replwrap.REPLWrapper.run_command

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Here are some resources how Ipython manages async

https://ipython.readthedocs.io/en/stable/interactive/autoawait.html

https://blog.jupyter.org/ipython-7-0-async-repl-a35ce050f7f7