Prepare for localization support zotero#82

* Add react-intl
* Automate message extraction & compilation into AST
* In devel, defaultMessage from the source code is used. In production
  that is removed and instead AST-compiled messages are used (which in
  future can be easilly used for localisation)

.gitignore

@@ -5,6 +5,7 @@ lib
 .DS_Store
 build
 data
+lang
 config/local*.json
 .npmrc
 .nyc_output

babel.config.cjs

@@ -16,8 +16,10 @@ const plugins = [
 		"corejs": 3,
 		"helpers": true,
 		"regenerator": false,
-	}]
-
+	}],
+	["formatjs", { removeDefaultMessage: !!process.env.NODE_ENV?.startsWith('prod') }]
 ];
 
+
+
 module.exports = { presets, plugins };