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/objects/class-limitations.php

@@ -30,7 +30,7 @@ class Limitations {
 	 * @since 2.0.0
 	 * @var array
 	 */
-	static $limitations_cache = [];
+	private static $limitations_cache = [];
 
 	/**
 	 * Version of the limitation schema.