Prep Plugin for release on WordPress.org

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.

views/base/list.php

@@ -50,9 +50,9 @@
 
 	</h1>
 
-	<?php if (isset($_GET['deleted'])) : ?>
+	<?php if (isset($_GET['deleted'])) : // phpcs:ignore WordPress.Security.NonceVerification ?>
 	<div id="message" class="updated notice wu-admin-notice notice-success is-dismissible below-h2">
-		<p><?php echo $page->get_labels()['deleted_message']; ?></p>
+		<p><?php echo esc_html($page->get_labels()['deleted_message']); ?></p>
 	</div>
 	<?php endif; ?>