- Adds new ConflictResolver class

- Executes URL query parameter conflict resolver action in Router class
- Adds unit tests

lib/Config/Initializer.php

@@ -4,6 +4,7 @@ namespace MailPoet\Config;
 use MailPoet\Cron\CronTrigger;
 use MailPoet\Router;
 use MailPoet\API;
+use MailPoet\Util\ConflictResolver;
 use MailPoet\WP\Notice as WPNotice;
 
 if(!defined('ABSPATH')) exit;
@@ -112,6 +113,7 @@ class Initializer {
       $this->setupShortcodes();
       $this->setupImages();
       $this->setupCronTrigger();
+      $this->setupConflictResolver();
 
       $this->plugin_initialized = true;
     } catch(\Exception $e) {
@@ -222,6 +224,11 @@ class Initializer {
     add_image_size('mailpoet_newsletter_max', 1320);
   }
 
+  function setupConflictResolver() {
+    $conflict_resolver = new ConflictResolver();
+    $conflict_resolver->init();
+  }
+
   function handleFailedInitialization($message) {
     return WPNotice::displayError($message);
   }