Build system: Replace Make by Meson

src/metadata.json.in

@@ -0,0 +1,11 @@
+{
+	"name": "Night Theme Switcher",
+	"description": "Make your desktop easy on the eye, day and night.",
+	"uuid": "@UUID@",
+	"gettext-domain": "@UUID@",
+	"settings-schema": "@DNS@",
+	"url": "https://nightthemeswitcher.romainvigier.fr",
+	"session-modes": ["unlock-dialog", "user"],
+	"shell-version": ["42"],
+	"version": @VERSION@
+}