Prepare design and key bindings for RTL localizations

[dascritch]

Arabic, Hebraic and others RTL (Right To Left) languages are usually using right-to-left timelines. A lot of abstraction work is to do there :

• [ ] check RTL support for native players
• [ ] reverse button groups
• [ ] reverse chapters list
• [ ] reverse timeline
• [ ] reverse key bidings (the most difficult ?)