Fix #300 - Feature/remove flag as language (#542)

* don't use flags to indicate languages #300

* cleaned code

* removed the filter and moved the logic to context.py

* cleaned code

* show the text in the local language

* cleaned code

* changed loop for list comprehension

* fix indentation

* ordered import

src/pretix/presale/templates/pretixpresale/event/base.html

@@ -37,10 +37,10 @@
         <div class="pull-right loginbox">
             {% if request.event.settings.locales|length > 1 %}
                 <div class="locales">
-                    {% for l in request.event.settings.locales %}
-                        <a href="{% url "presale:locale.set" %}?locale={{ l }}&next={{ request.path }}%3F{{ request.META.QUERY_STRING|urlencode }}"
-                            class="{% if l == request.LANGUAGE_CODE %}active{% endif %}"
-                            ><img src="{% static "pretixbase/img/flags/"|add:l|add:".png" %}"/></a>
+                    {% for l in languages %}
+                        <a href="{% url "presale:locale.set" %}?locale={{ l.code }}&next={{ request.path }}%3F{{ request.META.QUERY_STRING|urlencode }}" class="{% if l.code == request.LANGUAGE_CODE %}active{% endif %}">
+                            {{ l.name_local }}
+                        </a>
                     {% endfor %}
                 </div>
             {% endif %}