v1.3.1

Changes from v1.3.0:

• Fix reify() to persist column name order.
• Fix rollup() to handle empty input. (#64)
• Fix distinct aggregate to use standard key function.
• Refactor: Use op methods internally.
• Refactor: Refine concat() early exit criteria.
• Refactor: Refine dedupe() implementation.
• Refactor: Use aggregate result arrays, not objects.
• Clean JSDoc for optional options.