feat: Add macros

- New footer macros
- New header macro
- Use macros in partials

source/screens/demo/components.njk

@@ -7,6 +7,7 @@ tags:
 {% set pageId = page.fileSlug %}
 
 {% extends "demo/_main.njk" %}
+{% import "hippie/macros/_footer.njk" as footer %}
 
 {% block title %}Komponenten{% endblock %}
 {% block head %}
@@ -57,6 +58,10 @@ tags:
 				<pre class="pre_code"><code>section.sec_main_status</code></pre>
 				<h2>&lt;h3&gt;</h2>
 				<h2>&lt;h4&gt;</h2>
+				<h2>&lt;footer&gt;</h2>
+				<div style="position:relative;height:256px;background-color:#b7e0f0;">
+					{{ footer.pinned() }}
+				</div>
 			</article>
 			<article>
 				<h1 id="grouping">Gruppierung</h1>