Deprecate $NS in doku.php

$NS is only used in lib/exe/{ajax,mediamanager}.php when no $ID context
is present. The two functions which use $NS in inc/template.php are only
called through those both endpoints, not through doku.php. In doku.php,
$ID is the only correct value, $NS is not kept synchronous with $ID.

Use getNS($ID) in functions which are called through doku.php.

doku.php

@@ -30,7 +30,10 @@ $old = error_reporting(E_ALL ^ E_NOTICE);
 //import variables
 $QUERY = trim($_REQUEST['id']);
 $ID    = getID();
+
+// deprecated 2011-01-14
 $NS    = getNS($ID);
+
 $REV   = $_REQUEST['rev'];
 $IDX   = $_REQUEST['idx'];
 $DATE  = $_REQUEST['date'];