Add a flatpak manifest file.

- The manifest file is generated by ./make-flatpak-manifest.py.
  It contains the latest versions of eris's dependencies.
- The manifest file can be checked with the build-flatpak.sh script.

build-flatpak.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+
+# Copyright (C) 2019 Andrew Hamilton. All rights reserved.
+# Licensed under the Artistic License 2.0.
+
+
+USAGE="Make a flatpak build of eris.
+
+Usage: build-flatpak.sh <manifest_path> <build_dir> <state_dir>
+
+e.g. # build-flatpak.sh com.github.ahamilton.eris.json eris-build flatpak-cache"
+
+
+if [ $# != 3 ]; then
+    echo "$USAGE"
+    exit 1
+fi
+
+
+set -e
+set -x
+
+
+MANIFEST_PATH="$1"
+BUILD_DIR="$2"
+STATE_DIR="$3"
+rm -rf "$STATE_DIR/build"
+flatpak-builder "$BUILD_DIR" "$MANIFEST_PATH" --force-clean \
+		--state-dir="$STATE_DIR"
+flatpak build "$BUILD_DIR" test-all
+flatpak build "$BUILD_DIR" eris
+echo "Build successfull: $BUILD_DIR"