[IMPROVED] Adding customizable error page to MPOS

* `.htaccess` is used to re-define the error documents
* redirects to `index.php?page=error&action=<code>`
* does not work for MPOS inside subfolders yet

Addresses #734. If this works we can add this to all the other themes.

public/.htaccess

@@ -1,3 +1,4 @@
+ErrorDocument 404 /index.php?page=error&action=404
 RedirectMatch 404 /templates(/|$)
 RedirectMatch 404 /include(/|$)
 RedirectMatch 404 /.git(/|$)

public/include/pages/error.inc.php

@@ -0,0 +1,9 @@
+<?php
+
+// Make sure we are called from index.php
+if (!defined('SECURITY'))
+    die('Hacking attempt');
+
+// Tempalte specifics
+$smarty->assign("CONTENT", "default.tpl");
+?>

public/include/pages/error/404.inc.php

@@ -0,0 +1,9 @@
+<?php
+
+// Make sure we are called from index.php
+if (!defined('SECURITY'))
+    die('Hacking attempt');
+
+// Tempalte specifics
+$smarty->assign("CONTENT", "default.tpl");
+?>

public/templates/mpos/error/404/default.tpl

@@ -0,0 +1,6 @@
+<article class="module width_full">
+  <header><h3>{$GLOBAL.website.name}</h3></header>
+  <div class="module_content">
+    <p>The page you requested was not found.</p>
+  </div>
+</article>

public/templates/mpos/error/default.tpl

@@ -0,0 +1,6 @@
+<article class="module width_full">
+  <header><h3>{$GLOBAL.website.name}</h3></header>
+  <div class="module_content">
+    <p>The page you requested was not found.</p>
+  </div>
+</article>