Forum view does not comply with XHTML 1.0 Strict

There are several problems here:
1) The same problem as in MDL-17707 but for the forum summary
2) The same problem as in MDL-17708 but for the file /moodle/mod/forum/view.php. So the line
echo '<p align="center">';
should be changed by the line
echo "<p style=\"text-align: center\">";