* new question type 'Multiple choices of thumbnails from a file gallery' ('g') to be able to make a multiple choice question using thumbnails from a file gallery (e.g. for voting the best 3 images of a gallery, ...),
  * new checkbox to specify if a question is mandatory,
  * new params to specify, for multiple choices questions, the minimum and maximum number of required answers (+ error message when needed),
  * fix bad vote check and reset votes values after question edit for options of type 'text',
  * deploy auto_query_args + smarty self_link / button / icon,
  * remove useless comments in some places,
  * remove some redondancy in some templates titles/subtitles,
  * avoid useless tests on $questions[ix].type value in 'tiki-take_survey.tpl',
  * new 'Create New Survey' button in 'tiki-list_surveys.tpl' navbar,
  * use famfamfam icons instead of old ones in 'tiki-list_surveys.tpl',
  * translate of 'Vote' string in 'tiki-survey_stats_survey.tpl'