Add initial site config, content and copy of "simple" theme.

themes/next.copyleft.org/templates/category.html

@@ -0,0 +1,8 @@
+{% extends "index.html" %}
+
+{% block title %}{{ SITENAME }} - {{ category }} category{% endblock %}
+
+{% block content_title %}
+<h2>Articles in the {{ category }} category</h2>
+{% endblock %}
+