Improved -rtl.css includes and several styling fixes

Changes:

 - Removed RTL SCSS artifacts
 - Reusable RTL scss includes
 - Several RTL fixes
The issue is `@cache_if_anonymous` caches the same page regardless of the language. In a multi-lingual site, this prevents the anonymous users from changing the language.

This change should fix it. If you think this change is only supposed to be in my own fork. I can revert back.