Restructure macros

- Split macros.html in per-edition files
- Create new snippets.html macro file with utterances snippet
- Move support.html to snippets.html as new macro
- Create new `latest_post` macro in 2nd edition macros.html

blog/templates/snippets.html

@@ -0,0 +1,21 @@
+{% macro support() %}
+<p>
+    Creating and <a href="{{ get_url(path="@/status-update/_index.md") }}">maintaining</a> this blog and the associated libraries is a lot of work, but I really enjoy doing it. By supporting me, you allow me to invest more time in new content, new features, and continuous maintenance.
+</p>
+<p>
+    The best way to support me is to <a href="https://github.com/sponsors/phil-opp"><em>sponsor me on GitHub</em></a>, since they don't charge any fees. If you prefer other platforms, I also have <a href="https://www.patreon.com/phil_opp"><em>Patreon</em></a> and <a href="https://donorbox.org/phil-opp"><em>Donorbox</em></a> accounts. The latter is the most flexible as it supports multiple currencies and one-time contributions.
+</p>
+<p>
+    Thank you!
+</p>
+{% endmacro support %}
+
+{% macro utterances() %}
+    <script src="https://utteranc.es/client.js"
+        data-repo="phil-opp/blog_os"
+        data-issue-term="url"
+        data-label="comments"
+        crossorigin="anonymous"
+        async>
+    </script>
+{% endmacro utterances %}