Add ability to add custom welcome template

This adds the ability to add a custom welcome template.
It works by simply adding a custom folder in the templates
directory and putting a email/html/welcome.html.twig and
email/text/welcome.txt.twig there (as you can read in the
README).

README.md

@@ -51,6 +51,14 @@ Go to `http://localhost:8080/` and you should be greeted by the MijnRood login p
 You can log in with `[email protected]` as email, and `admin` as password.
 Look at `src/DataFixtures/` to see an overview of all test data, including other accounts.
 
+## Extra configuration
+
+### Custom welcome mail
+
+To add a custom welcome email, put the two templates (html and plain text) in:
+
+`templates/custom/email/welcome.html.twig` and `templates/custom/email/welcome.html.txt`
+
 ## Contributing
 
 You can generate new migrations with:

src/Controller/Admin/MembershipApplicationCrud.php

@@ -128,15 +128,21 @@ public function acceptApplication(AdminContext $context)
         $em->remove($application);
         $em->flush();
 
+	$templatePrefix = '';
+
+	if (is_dir($this->getParameter('kernel.project_dir') . '/templates/custom')) {
+	    $templatePrefix = 'custom/';
+	}
+
         $message = (new Email())
             ->subject("Welkom bij $organizationName!")
             ->to(new Address($member->getEmail(), $member->getFullName()))
             ->from(new Address($noreply,$organizationName))
             ->html(
-                $this->renderView('email/html/welcome.html.twig', ['member' => $member])
+                $this->renderView($templatePrefix . 'email/html/welcome.html.twig', ['member' => $member])
             )
             ->text(
-                $this->renderView('email/text/welcome.txt.twig', ['member' => $member])
+                $this->renderView($templatePrefix . 'email/text/welcome.txt.twig', ['member' => $member])
             );
         $mailer->send($message);