support arbitrary source URLs, closes #87

Author: anarcat

alabaster/layout.html

@@ -51,9 +51,14 @@
       {% endif %}
       {%- if show_source and has_source and sourcename %}
       {% if show_copyright or theme_show_powered_by %}|{% endif %}
+      {%- if source_url_prefix %}
+      <a href="{{ source_url_prefix }}{{ pagename }}{{ source_suffix }}"
+          rel="nofollow">{{ _('Page source') }}</a>
+      {%- else %}
       <a href="{{ pathto('_sources/' + sourcename, true)|e }}"
           rel="nofollow">{{ _('Page source') }}</a>
       {%- endif %}
+      {%- endif %}
     </div>
 
     {% if theme_github_banner|lower != 'false' %}