v2.8.0

• Add d3.nice.
• Add d3.every.
• Add d3.some.
• Add d3.filter.
• Add d3.map.
• Add d3.reduce.
• Add d3.reverse.
• Add d3.sort.
• Add d3.difference.
• Add d3.disjoint.
• Add d3.intersection.
• Add d3.superset.
• Add d3.subset.
• Add d3.union.
• Fix d3.bin to nice the domain by default, ensuring uniform bin widths.