Resolve "Allow site-local configuration of available languages"

Closes #261 (closed)

aleksis/core/templates/core/partials/language_form.html

 {# -*- engine:django -*- #}
 
-{% load i18n %}
+{% load i18n data_helpers %}
 
 
 <form action="{% url 'set_language' %}" method="post" class="language-form">
@@ -8,7 +8,7 @@
   <input name="next" type="hidden" value="{{ request.get_full_path }}">
 
   {% get_current_language as LANGUAGE_CODE %}
-  {% get_available_languages as LANGUAGES %}
+  {% get_enabled_languages as LANGUAGES %}
   {% get_language_info_list for LANGUAGES as languages %}
 
   {# Select #}