Extract user reading time logic in a single place

Extract user reading time computation in a single place under Entry to avoid duplication.

This will also fix reading time computation for short entries.

RuleTagger logic is slightly changed as we will round when filtering, which will be
consistent with frontend display.

src/Wallabag/CoreBundle/Entity/Entry.php

@@ -658,6 +658,14 @@ class Entry
         $this->readingTime = $readingTime;
     }
 
+    /**
+     * @return float
+     */
+    public function getUserReadingTime()
+    {
+        return round($this->readingTime / $this->getUser()->getConfig()->getReadingSpeed() * 200);
+    }
+
     /**
      * @return string
      */

src/Wallabag/CoreBundle/Helper/EntriesExport.php

@@ -210,7 +210,7 @@ class EntriesExport
                 $publishedDate = $entry->getPublishedAt()->format('Y-m-d');
             }
 
-            $readingTime = round($entry->getReadingTime() / $user->getConfig()->getReadingSpeed() * 200);
+            $readingTime = $entry->getUserReadingTime();
 
             $titlepage = $content_start .
                 '<h1>' . $entry->getTitle() . '</h1>' .
@@ -331,7 +331,7 @@ class EntriesExport
                 $authors = implode(',', $publishedBy);
             }
 
-            $readingTime = $entry->getReadingTime() / $user->getConfig()->getReadingSpeed() * 200;
+            $readingTime = $entry->getUserReadingTime();
 
             $pdf->addPage();
             $html = '<h1>' . $entry->getTitle() . '</h1>' .

src/Wallabag/CoreBundle/Helper/RuleBasedTagger.php

@@ -133,7 +133,7 @@ class RuleBasedTagger
     private function fixEntry(Entry $entry)
     {
         $clonedEntry = clone $entry;
-        $clonedEntry->setReadingTime($entry->getReadingTime() / $entry->getUser()->getConfig()->getReadingSpeed() * 200);
+        $clonedEntry->setReadingTime($entry->getUserReadingTime());
 
         return $clonedEntry;
     }

src/Wallabag/CoreBundle/Resources/views/Entry/_reading_time.html.twig

@@ -1,7 +1,7 @@
-{% set reading_time = entry.readingTime / app.user.config.readingSpeed * 200 %}
+{% set reading_time = entry.userReadingTime %}
 <i class="material-icons grey-text">timer</i>
 {% if reading_time > 0 %}
-    <span>{{ 'entry.list.reading_time_minutes_short'|trans({'%readingTime%': reading_time|round}) }}</span>
+    <span>{{ 'entry.list.reading_time_minutes_short'|trans({'%readingTime%': reading_time}) }}</span>
 {% else %}
     <span>{{ 'entry.list.reading_time_less_one_minute_short'|trans|raw }}</span>
 {% endif %}