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

src/Wallabag/CoreBundle/Helper/DetectActiveTheme.php

@@ -1,72 +0,0 @@
-<?php
-
-namespace Wallabag\CoreBundle\Helper;
-
-use Liip\ThemeBundle\Helper\DeviceDetectionInterface;
-use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;
-use Wallabag\UserBundle\Entity\User;
-
-/**
- * This class intend to detect the active theme for the logged in user.
- * It will retrieve the configured theme of the user.
- *
- * If no user where logged in, it will return the default theme
- */
-class DetectActiveTheme implements DeviceDetectionInterface
-{
-    protected $tokenStorage;
-    protected $defaultTheme;
-    protected $themes;
-
-    /**
-     * @param TokenStorageInterface $tokenStorage Needed to retrieve the current user
-     * @param string                $defaultTheme Default theme when user isn't logged in
-     * @param array                 $themes       Themes come from the LiipThemeBundle (liip_theme.themes)
-     */
-    public function __construct(TokenStorageInterface $tokenStorage, $defaultTheme, $themes)
-    {
-        $this->tokenStorage = $tokenStorage;
-        $this->defaultTheme = $defaultTheme;
-        $this->themes = $themes;
-    }
-
-    public function setUserAgent($userAgent)
-    {
-    }
-
-    /**
-     * This should return the active theme for the logged in user.
-     *
-     * Default theme for:
-     *     - anonymous user
-     *     - user without a config (shouldn't happen ..)
-     *
-     * @return string
-     */
-    public function getType()
-    {
-        $token = $this->tokenStorage->getToken();
-
-        if (null === $token) {
-            return $this->defaultTheme;
-        }
-
-        $user = $token->getUser();
-
-        if (!$user instanceof User) {
-            return $this->defaultTheme;
-        }
-
-        $config = $user->getConfig();
-
-        if (!$config) {
-            return $this->defaultTheme;
-        }
-
-        if (!\in_array($config->getTheme(), $this->themes, true)) {
-            return $this->defaultTheme;
-        }
-
-        return $config->getTheme();
-    }
-}