MAPG-86 add 404 error page

views/error/404.php

@@ -0,0 +1,7 @@
+<?php require ROOT . '/views/templates/main_header.php'; ?>
+<?php require ROOT . '/views/templates/header.php'; ?>
+<div class="main">
+    <h2>404 | Page not found</h2>
+    <p>The requested URL was not found on this server. <a href="/" title="MapGuesser">Back to start.</a></p>
+</div>
+<?php require ROOT . '/views/templates/main_footer.php'; ?>