Merge pull request #54 from chamilo/1.9.x

1.9.x
Update survey.lib.php
Update preview.php
Update fillsurvey.php

Some fixes when accessing anonymous survey -refs #6829
Update fillsurvey.php

Bug Fixed
Update fillsurvey.php
Merge pull request #273 from ycastillo/yoselyn1.9.8

Yoselyn1.9.8