allow age calculation on NULL birthdate and allow age to be null

+ improve translation of age

src/Bundle/ChillMainBundle/translations/messages+intl-icu.fr.yaml

@@ -0,0 +1,6 @@
+years_old: >-
+    {age, plural, 
+        one {# an}
+        many {# ans}
+        other {# ans}
+    }

src/Bundle/ChillPersonBundle/Entity/Person.php

@@ -734,9 +734,13 @@ class Person implements HasCenterInterface, TrackCreationInterface, TrackUpdateI
         return $this->birthdate;
     }
     
-    public function getAge(): int 
+    public function getAge(): ?int 
     {
-        return date_diff($this->birthdate, date_create('now'))->format("%y");
+        if ($this->birthdate instanceof \DateTimeInterface) {
+            return date_diff($this->birthdate, date_create('now'))->format("%y");
+        }
+
+        return null;
     }
 
     /**

src/Bundle/ChillPersonBundle/Resources/views/Person/banner.html.twig

@@ -76,10 +76,10 @@
                         {{ 'Unknown date of birth'|trans }}
                     {% else %}
                         {{ person.birthdate|format_date('short') }}
+                        <span class="age">
+                          {{ 'years_old'|trans({ 'age': person.age }) }}
+                        </span>
                     {% endif %}
-                    <span class="age">
-                        {{ person.age ~ ((person.age > 1) ? ' ans' : ' an') }}
-                    </span>
                 </div>
                 
                 {%- if chill_person.fields.nationality == 'visible' -%}

src/Bundle/ChillPersonBundle/Tests/Controller/PersonControllerUpdateTest.php

@@ -102,7 +102,7 @@ class PersonControllerUpdateTest extends WebTestCase
     public function testHiddenFielsArePresent()
     {
         $crawler = $this->client->request('GET', $this->editUrl);
-
+var_dump($crawler->text());
         $configurables = array('placeOfBirth', 'phonenumber', 'email',
             'countryOfBirth', 'nationality', 'spokenLanguages', 'maritalStatus');
         $form = $crawler->selectButton('Enregistrer')->form(); //;