Add meson build system (#1)

Initial meson build system support. We do not create .desktop file yet, but we need an option to open media files from GUI first anyway.

bin/com.github.rafostar.Clapper.in

@@ -0,0 +1,12 @@
+#!@GJS@
+
+const Package = imports.package;
+
+Package.init({
+  name: '@PACKAGE_NAME@',
+  version: '@PACKAGE_VERSION@',
+  prefix: '@prefix@',
+  libdir: '@libdir@',
+  datadir: '@datadir@',
+});
+Package.run(imports.main);