Small Multiples III/a - decoupled rendering

A logarithmic variant of the small multiples example created by Mike Bostock with the following goals:

1. no data mutation
2. reduced coupling between rendering vs. the data and layout calculations that are invariant of the choice of the rendering substrate (SVG, DOM, Canvas, WebGL etc.)
3. linear data flow
4. easier reuse and modularization

Original forked from mbostock‘s block: Small Multiples III to compare the Local Variables proposal with my preference shown here for avoiding the model / render coupling in the first place.

Minor functional changes that are irrelevant from the viewpoint of the data flow:

• use of a log scale due to the long time period
• instead of [0, maxPrice] the price scale just uses [minPrice, maxPrice] for the domain