Use generic typing for Scales. [make-uniq-generic]

```
Abstract.Scale -> Abstract.Scale<D,R>
QuantitativeScale<D> extends Scale<D, number>
OrdinalScale extends Scale<string, number>
ColorScale extends Scale<string, string>
InterpolatedColorScale extends Scale<number, string>
```

Changes: `InterpolatedColorScale` no longer inherits `QuantitiveScale`
Some vars on scales made public to fix mysterious ts issues
`<any>`s added into Plots so as to reduce the size of this PR.

QE: Recommend checking `InterpolatedColorScales` in particular