Make Sitemapper functions static as they were used as static functions

All calls to the Sitemapper were static function calls, this caused
notices because they weren't static, with this commit they are marked as
static. Furthermore two FIXME comments were removed as dbglog now checks
if debugging is enabled.

inc/Sitemapper.php

@@ -25,7 +25,7 @@ class Sitemapper {
      * @link   https://www.google.com/webmasters/sitemaps/docs/en/about.html
      * @link   http://www.sitemaps.org/
      */
-    public function generate(){
+    public static function generate(){
         global $conf;
         if($conf['sitemap'] < 1 || !is_numeric($conf['sitemap'])) return false;
 
@@ -39,11 +39,11 @@ public function generate(){
 
         if(@filesize($sitemap) &&
            @filemtime($sitemap) > (time()-($conf['sitemap']*86400))){ // 60*60*24=86400
-            dbglog('Sitemapper::generate(): Sitemap up to date'); // FIXME: only in debug mode
+            dbglog('Sitemapper::generate(): Sitemap up to date');
             return false;
         }
 
-        dbglog("Sitemapper::generate(): using $sitemap"); // FIXME: Only in debug mode
+        dbglog("Sitemapper::generate(): using $sitemap");
 
         $pages = idx_get_indexer()->getPages();
         dbglog('Sitemapper::generate(): creating sitemap using '.count($pages).' pages');
@@ -77,7 +77,7 @@ public function generate(){
      * @return string The sitemap XML.
      * @author Michael Hamann
      */
-    private function getXML($items) {
+    private static function getXML($items) {
         ob_start();
         echo '<?xml version="1.0" encoding="UTF-8"?>'.NL;
         echo '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">'.NL;
@@ -96,7 +96,7 @@ private function getXML($items) {
      * @return The path to the sitemap file.
      * @author Michael Hamann
      */
-    public function getFilePath() {
+    public static function getFilePath() {
         global $conf;
 
         $sitemap = $conf['cachedir'].'/sitemap.xml';
@@ -113,7 +113,7 @@ public function getFilePath() {
      * 
      * @author Michael Hamann
      */
-    public function pingSearchEngines() {
+    public static function pingSearchEngines() {
         //ping search engines...
         $http = new DokuHTTPClient();
         $http->timeout = 8;