Make it possible to exit ipython even if you have threaded servers running.

[MarcSkovMadsen]

I'm using panel==1.4.1

If I .show() a Panel component in ipython with threaded=True I cannot exit it with exit(). I would expect to be able to do that.

Reproducible Example

Fix

I believe what needs to be done is to make the thread a daemon thread.

Additional Context

This is not only a problem in ipython. Its a problem in most context as you cannot exit your program in a graceful manner.

In https://discourse.holoviz.org/t/overwhelmed-by-with-holoviews-hvplot-panel-workflow-permutations-concepts/7141/2 I have to teach a user to get a handle on the server such that he can gracefully exit an interactive terminal later. That is friction.