Flatpak package on flathub

It would be nice if you could publish this as a [flatpak](https://flatpak.org/) on [flathub](https://flathub.org/) e.g.

Flatpaks are a new software distribution mechanism for Linux distros, can thus installed on any distro and are easy to update. They are easy to install _and_ update and work on all Linux distros.
Also, if you publish it on _FlatHub_ you may grow your user base given many distros include that and it is a common software source, so your app can be discovered more easily.

Here is [how to get started](http://docs.flatpak.org/en/latest/getting-started.html).

Start with the linked Flatpak getting-started guide and inspect the Flathub publishing requirements for xSTUDIO. Done means xSTUDIO is packaged as a Flatpak and published on Flathub.

Written by the indexing model from the issue text.