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

views/dashboard-widgets/invoices.php

@@ -17,7 +17,7 @@
 
 			<h3 class="wu-m-0 <?php echo wu_env_picker('', 'wu-widget-title'); ?>">
 
-			<?php echo $title; ?>
+			<?php echo esc_html($title); ?>
 
 			</h3>
 
@@ -47,15 +47,15 @@
 
                 </a>',
 					$payment->get_invoice_url(),
-					esc_attr__('Download Invoice', 'wp-ultimo')
+					esc_html__('Download Invoice', 'wp-multisite-waas')
 				);
 
 				$payment_column = $payment->get_status() === 'pending' ? [
 					'pay_now' => [
 						'url'   => add_query_arg(['payment' => $payment->get_hash()], wu_get_registration_url()),
 						'icon'  => 'dashicons-wu-credit-card wu-align-middle wu-mr-1',
-						'label' => __('Go to payment', 'wp-ultimo'),
-						'value' => __('Pay Now', 'wp-ultimo'),
+						'label' => esc_html__('Go to payment', 'wp-multisite-waas'),
+						'value' => esc_html__('Pay Now', 'wp-multisite-waas'),
 					],
 				] : [];