Move to Symfony Flex

The structure changed completely.
Bundles are gone. Everything is flatten in the folder `src`.
I separated import & api controllers to avoid _pollution_ in the main controller folder.

templates/Entry/_reading_time.html.twig

@@ -0,0 +1,7 @@
+{% set reading_time = entry.readingTime / app.user.config.readingSpeed * 200 %}
+<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>
+{% else %}
+    <span>{{ 'entry.list.reading_time_less_one_minute_short'|trans|raw }}</span>
+{% endif %}