Rewrite the code infrastructure to generate a flatpak package on CI
flatpak: add a builder to build nightly flatpak
graphview: port to gtk4 version 0.4.1
app: port to gtk4 version 0.4.1
pipeline: fix a small issue with properties
gitlab-ci: disable rust-doc
meson: improve application install
ReadMe: update contents
gitignore: add new patterns
Edited by Stéphane Cerveau