3.0 Notes AKA ideas that require breaking changes

[gampleman]

Note: None of this is going to happen any time soon. The last breaking change we made was forced by a new version of Elm. But it is a good idea to keep a wish list of things to change in the future.

• sequential scale can easily support axes, but don't at the moment
• Loosen type signature of invertExtent to support threshold scales.
• Use partial application for scales to simplify type signatures.
• Switch from record to list style for band/point configs.
• Change architecture of Force to allow for nicer custom forces as well as better dead code elimination
• Better version of Interpolation.list #144
• Axis ticks color #65
• Surely Shape.stack can be made more intuitive.

See also #10.