[IMP] tools: sanitizer: add and clean sanitize options

Now having

 * sanitize: run the sanitizer to clean the html (removing javascripts,
   unwanted tags, ...)
 * sanitize_tags: only a subset of tags is allowed in html content.
   Unwelcomed tags are remove dand their content stripped.
 * sanitize_attributes: only a subset of attributes is allowed.
 * sanitize_style: only a subset of style attributes is allowed. Style
   attributes are parsed to keep only a white list.
 * strip_style: all style is removed. It bypasses sanitize_style as there
   is no need to sanitize something that is removed.
 * strip_classes: remove class attributes

Fields parameters have also been updated to match the sanitize options. Html
fields by default are sanitized with sanitize_tags activated but without any
further options. All addons have been updated to match the new options
according to their previous behavior.