Added editing function for pages (using tinymce).

Added editing pages for footer, banner, aside.
Added page overview.
Added public page.
Added settings page.
Added generator for embed pseudocodes.

edit/editHTMLPage.php

@@ -0,0 +1,97 @@
+<?PHP
+/**
+ * This page offers the opportunity to edit static page elements: the side bar and the footer.
+ */
+
+/*
+ * Require files and ensure environment.
+ */
+
+require_once __DIR__ . "/inc/functions.php";
+
+ensureEnvironment();            // Ensure existence of system files.
+$translations = loadLanguage(); // Load translations.
+ensureBackendEnv();             // Ensure session is started etc.
+$pages = loadPages();           // Load overview of pages.
+
+/*
+ * Load contents
+ */
+
+// Check for vars.
+loadHttpToGlobals(["id", "task", "content"]);
+
+define("targetFile", __DIR__ . "/../data/$id.htm");
+
+if (!isset($id) or !in_array($id, ['footer', 'aside', 'banner'])) {
+    echo printErrorPage($translations['specifyToEdit']); return;
+}
+
+// Read file contents if there is no new content sent by $_POST.
+
+if (!isset($content)) {
+    if (file_exists(targetFile)) {
+        $content = file_get_contents(targetFile);
+    }
+    else $content = "";
+}
+
+// Set page title
+
+$pageTitle = $translations['edit'] . ': ' . $translations[$id];
+
+/*
+ * Store if need be
+ */
+if (isset($task) and $task == "update") {
+
+    file_put_contents(targetFile, $content, LOCK_EX);
+
+    header('Location: editHTMLPage.php?id=' . $id);
+    return;
+
+}
+
+
+/*
+ * Output
+ */
+
+if (!isset($public)) $public = false;
+
+echo printBackendHead($pageTitle);
+echo printBackendHeader($pageTitle, $translations["help$id"]);
+
+echo '
+<div id="mainWrapper">
+';
+
+echo printBackendNav($translations);
+
+echo '
+    <main class="noPadding">
+    <form action="" method="POST">
+
+        <textarea type="text" name="content" id="pageContent" class="mceEditor" placeholder="' . $translations['staticPageTitle'] . '" required>';
+if (isset($content)) echo $content;
+echo '
+        </textarea>
+
+        <span>
+            <button type="submit">' . $translations['submit'] . '</button>
+            ' . printHiddenInputs(["task" => "update", "id" => $id]) . '
+        </span>
+
+    </form>
+    </main>
+</div>
+
+
+    <script src="./js/tinymce471/js/tinymce/tinymce.min.js"></script>
+    <script type="text/javascript" src="./js/runTinyMCE.js"></script>
+
+';
+
+echo printBackendEnd();
+
+?>