v2.0: list of breaking changes to be discussed

[j-fu]

Improvements worth a breaking change

• Singleton type pattern for backend dispatch Replace plottertypes by Singleton #109
• Iterator API Iterator api #23 (this is not necessarily breaking)

[jpthiele]

I also roughly remember some discussion around adding some depwarn around setting colors as tuples instead of proper RGB Type from Colors when we fixed the type piracy.