Fixes:
* Sanitize user-provided content in HTML (Fixes#2193)
* Fix encoding of search query in prev/next pages (Fixes#2229)
* Fix some issues introduced with #2196:
- Fix alignment of all <h3> elements (Move the inline style from the parent to the <h3> element)
- Add missing comma on 'dir' HTML attribute (Typo introduced by PR #2196)
Code cleaning:
* Remove unnecessary 'each_sclice' + 'each' double loop in ECR files
* Clean the player's <source> list generation code (in player.ecr)
