Prep Plugin for release on WordPress.org (#23)

* Update translation text domain
* Escape everything that should be escaped.
* Add nonce checks where needed.
* Sanitize all inputs.
* Apply Code style changes across the codebase.
* Correct many deprecation notices.
* Optimize load order of many filters.
* Add Proper Build script
* Use emojii flags
* Fix i18n deprecation  notice for translating too early
* Put all scripts in footer and load async

inc/traits/trait-wp-ultimo-subscription-deprecated.php

@@ -38,7 +38,7 @@ trait WP_Ultimo_Subscription_Deprecated {
 		 *
 		 * @since 2.0.0
 		 */
-		_doing_it_wrong($key, __('Membership keys should not be accessed directly', 'wp-ultimo'), '2.0.0');
+		_doing_it_wrong($key, __('Membership keys should not be accessed directly', 'wp-multisite-waas'), '2.0.0');
 
 		return $value;
 	}