Opensurvey improvements

Because there are a lot of commits, here I summarize the changes:

* Disabled public access to poll creation
* Fixed lot of non-translated strings
* Improved feedback when no input was filled
* Fixed XSS in both public and admin pages of opensurvey module
* Removed feature to allow everyone edit other users' vote
* Integrated opensurvey creation process pages in Dolibarr look-and-feel
* Removed email and author name from the survey creation page as they are now get from the linked author
* Added security checks to all the pages to behave as set in user permissions
* Removed odd module configuration page
* Added triggers OPENSURVEY_CREATE and OPENSURVEY_DELETE
* Renamed SurveyResults/Preview tab to SurveyResults and removed the preview of the poll as it wasn't useful
* Changes to llx_opensurvey_sondage table to improve the table definition
* Removed unused code and created some functions in Opensurveysondage class to remove duplicated code