Shell + page loading

And:
- some basic stylesheet i found for basic html elements
- a global lua method for navigating pages

assets/pages/testPage.rml

@@ -0,0 +1,5 @@
+<div id="page-root" data-model="testPage" class="page">
+    <h1>Test page</h1>
+    <p>{{greeting}}</p>
+    <button id="test-btn">Button clicked: {{counter}} times</button>
+</div>