Better default settings for projections. Slightly faster, although future optimizations are planned.
New d3.geo.transform API. Rather than closures, use `this.stream`. TODO `this.sink`, `this.next`? The new implementation is faster: rather than each method being implemented as a closure, it defines a factory method for creating transform instances.
Removed support for the fallback projection pipeline, d3.geoProjection(*function*). Simplified how projection pipelines are cached internally (an undocumented feature of 3.x).
Renamed *circle*.origin ↦ *circle*.center and *circle*.angle ↦ *circle*.radius.