Major step for build process

- updated to 0.4.0
- corrected license for npm
- update to gulp 4
- updated all dependencies
- new and removed packages, see `package.json`
- changed file structure, renamed `pages` to `screen` and new `data` 
folder
- complete change of `gulpfile.js` with similar output

source/screens/demo.njk

@@ -0,0 +1,53 @@
+<!-- page-index.njk -->
+{% set pageId = "index" %}
+{% set pageClass = "height_full" %}
+
+{% extends "demo/default.njk" %}
+
+{% block title %}Index{% endblock %}
+{% block head %}
+{{ super() }}
+{% endblock %}
+
+{% block body_content %}
+<div class="wrap">
+  <div class="hello">
+    <h2>This is {{hippie.brand | upper}}</h2>
+    <p>You can start using it by replacing this file with your own index page.</p>
+    <p>To do this you need to open the file <code>/gulpfile.js</code> and comment out the line <code>index: "demo.html",</code>. Then you need to place your index file (<code>index.njk</code>) into the folder <code>/source/pages</code>.</p>
+    <p>For a very basic start you can make a copy of the demo page <code>blank.njk</code>. You can find it at <code>/source/pages/demo</code>.</p>
+    <p>The <i>demo</i> folder contains an overview of all elements and also examples for style combinations and even whole page layouts.<br/>Follow the white rabbit.</p>
+    <h3>Overview</h3>
+    <ul class="list_link">
+      <!-- Loops through "demoadditionallinks" array -->
+      {% for link in data.demoadditionallinks %}
+      <li><a href="{{link.href}}">{{link.text}}</a></li>
+      {% endfor %}
+    </ul>
+    <div class="pos_rel">
+      <pre class="txt_tiny txt_white pos_abs pin_down pin_right">
+  ()()
+  (..)
+C(")(")</pre>
+      <h3>Demo Pages</h3>
+  </div>
+    <ul class="list_link">
+      <!-- Loops through "demo-links" array -->
+      {% for link in data.demolinks %}
+      <li><a href="{{link.href}}">{{link.text}}</a></li>
+      {% endfor %}
+    </ul>
+  </div>
+</div>
+{% endblock %}
+
+{% block script %}
+{{ super() }}
+<script src="./js/{{hippie.jsFile}}.min.js" type="text/javascript"></script>
+<script type="text/javascript">
+// Page specific
+// ------------------------------------------------------------------------------
+$( document ).ready(function() {
+});
+</script>
+{% endblock %}