Remove LiipThemeBundle

As baggy theme was removed and material is the only remaining theme, we don't need a theme switched anymore.
So:
- move all `*.twig` files from the material theme folder to the root
- remove useless translations

tests/Wallabag/CoreBundle/Controller/ConfigControllerTest.php

@@ -55,7 +55,6 @@ class ConfigControllerTest extends WallabagCoreTestCase
         $form = $crawler->filter('button[id=config_save]')->form();
 
         $data = [
-            'config[theme]' => 'material',
             'config[items_per_page]' => '30',
             'config[reading_speed]' => '100',
             'config[action_mark_as_read]' => '0',
@@ -120,7 +119,6 @@ class ConfigControllerTest extends WallabagCoreTestCase
     {
         return [
             [[
-                'config[theme]' => 'material',
                 'config[items_per_page]' => '',
                 'config[language]' => 'en',
             ]],
@@ -837,7 +835,6 @@ class ConfigControllerTest extends WallabagCoreTestCase
 
         $config = new ConfigEntity($user);
 
-        $config->setTheme('material');
         $config->setItemsPerPage(30);
         $config->setReadingSpeed(200);
         $config->setLanguage('en');

tests/Wallabag/CoreBundle/Controller/EntryControllerTest.php

@@ -86,7 +86,6 @@ class EntryControllerTest extends WallabagCoreTestCase
     public function testGetNew()
     {
         $this->logInAs('admin');
-        $this->useTheme('material');
         $client = $this->getClient();
 
         $crawler = $client->request('GET', '/new');

tests/Wallabag/CoreBundle/Helper/RedirectTest.php

@@ -41,7 +41,6 @@ class RedirectTest extends TestCase
         $user->addRole('ROLE_SUPER_ADMIN');
 
         $config = new Config($user);
-        $config->setTheme('material');
         $config->setItemsPerPage(30);
         $config->setReadingSpeed(200);
         $config->setLanguage('en');

tests/Wallabag/CoreBundle/WallabagCoreTestCase.php

@@ -11,7 +11,6 @@ use Symfony\Component\Console\Input\ArrayInput;
 use Symfony\Component\Console\Output\NullOutput;
 use Symfony\Component\HttpFoundation\Session\SessionInterface;
 use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;
-use Wallabag\CoreBundle\Entity\Config;
 use Wallabag\UserBundle\Entity\User;
 
 abstract class WallabagCoreTestCase extends WebTestCase
@@ -152,14 +151,6 @@ abstract class WallabagCoreTestCase extends WebTestCase
         return $this->getLoggedInUser()->getId();
     }
 
-    public function useTheme($theme)
-    {
-        $config = $this->getEntityManager()->getRepository(Config::class)->findOneByUser($this->getLoggedInUser());
-        $config->setTheme($theme);
-        $this->getEntityManager()->persist($config);
-        $this->getEntityManager()->flush();
-    }
-
     /**
      * Check if Redis is installed.
      * If not, mark test as skip.

tests/Wallabag/UserBundle/EventListener/CreateConfigListenerTest.php

@@ -32,7 +32,6 @@ class CreateConfigListenerTest extends TestCase
 
         $this->listener = new CreateConfigListener(
             $this->em,
-            'material',
             20,
             50,
             'fr',
@@ -61,7 +60,6 @@ class CreateConfigListenerTest extends TestCase
         );
 
         $config = new Config($user);
-        $config->setTheme('material');
         $config->setItemsPerPage(20);
         $config->setFeedLimit(50);
         $config->setLanguage('fr');