Add Flatpak image build

flatpak/build.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+cd "$(dirname "$(readlink -f "$0")")/.." || error "Failed to switch to correct directory"
+
+./gradlew packageReleaseUberJarForCurrentOS
+
+flatpak-builder --ccache --force-clean  --repo=flatpak/_repo ./flatpak/_build ./flatpak/ch.dissem.YAEP.yml
+
+if [ "$1" = "bundle" ] || [ "$1" = "install" ]; then
+  echo "Build is done, creating bundle now. This may take a while..."
+  flatpak build-bundle flatpak/_repo "flatpak/YAEP-$(arch)-1.0.0.flatpak" ch.dissem.YAEP
+fi
+
+if [ "$1" = "install" ]; then
+  flatpak install "flatpak/YAEP-$(arch)-1.0.0.flatpak"
+fi