Rename 'reshare' to 'boost' in templates and PO

For now it might be enough to only reword 'reshare' to 'boost' in the
frontend. The code can continue to use 'reshare'.

Includes the most recent German translation.

Fixes #74

templates/users/details.html.tera

@@ -18,7 +18,7 @@
         {{ user.summary | safe }}
     </div>
 
-    {% if recents | length != 0 %}    
+    {% if recents | length != 0 %}
         <h2>{{ "Latest articles" | _ }}</h2>
         <div class="cards">
             {% for article in recents %}
@@ -28,7 +28,7 @@
     {% endif %}
 
     {% if reshares | length != 0 %}
-        <h2>{{ "Recently reshared" | _ }}</h2>
+        <h2>{{ "Recently boosted" | _ }}</h2>
         <div class="cards">
             {% for article in reshares %}
                 {{ macros::post_card(article=article) }}