#3 [Packaging] Make this program available as flatpak package on FlatHub

[nokia808]

Hi. It is very useful to make this program available as flatpak package on FlatHub. This way you will make this program available for almost any Linux distros & users, because flatpak is universal generic Linux package with secure features by default & easy & convenient installation & automatic update mechanism.

Please note the following:

1. home page of FlatHub is:
   https://www.flathub.org/home
2. FlatHub repositories are at:
   https://github.com/flathub
3. when some one like to add package to FlatHub, she/he need to open PR at:
   https://github.com/flathub/flathub/pulls
4. FlatHub differ from snap by being allow any one to package not only developers of packages. So packages on FlatHub are of 2 types: those packaged by developer(s) of program, & those packaged by other peoples.
5. all packages on FlatHub are signed .....
6. even if person other than the original developer(s) maintain the package on FlatHub, FlatHub team try as much as possible to make developer(s) authorized to repositories at least to monitor & follow up the packaging ......
7. FlatHub allow both open & closed source packages. But regarding open source packages, the FlatHub team insisting on packager to make them deterministic (reproducible).