Current state of ObservatoryCore on Linux

Hello all,

the maintainer of ObservatoryCore, Xjph, has recently announced that Linux support will be completely dropped. They are planning on rewriting the UI with WinForms, which is not compatible with Linux. To directly quote Xjph from [their post on the Frontier forums](https://forums.frontier.co.uk/threads/521544/page-73#post-10115777):

> I originally chose AvaloniaUI as my UI framework because it [...] was compatible with both Windows and Linux [...]. Well no Linux build I ever did was in what I would consider a "releasable" state, and on top of that my use of AvaloniaUI has not really been a great time.
For Linux users who were perhaps holding onto the hope of an official Linux release, this is unfortunately the final nail in the coffin for that particular goal. Sorry I never made it work.

This means that all future updates to ObservatoryCore will not be compatible with Linux. I will try to maintain a fork that keeps using Avalonia, but I can't guarantee anything. I don't know how much work it's going to be or if it is even possible, especially since I'm really not that skilled in C#.

Let me know your thoughts.