v0.2.8

Please see the 0.2.8 release notes for more!

• Add rank and quantile map transform methods.
• Add the shuffle transform.
• Add asymmetric inset options for position scales.
• Fix the default range for the radius (r) scale to never be greater than 30px.
• Fix how the bin, group, and stack transforms consume (or propagate) options.
• Fix the count reducer to no longer inherit the channel name as a default label.
• Fix the bin transform to coerce to dates when the thresholds are temporal.
• Fix text marks to default strokeLinejoin to round.