v0.6.8

Please see the 0.6.8 release notes for more!

• The x and y scale default domains now incorporate geometry. #1468
• The stack transform’s order option now accepts a comparator. #1195 #1642
• The stack transform’s order option now supports -order descending shorthand. #1642 #1613
• Fix color legends when the domain or range has extra elements, and issue a warning. #1633 #1632
• Fix the default stroke with the hexbin transform when used with the tip mark. #1641
• Fix duplicate application of scale transforms with the tip mark option. #1645
• Fix erroneous implicit title channel with the tip mark option. #1658 #1657
• Fix spurious high-cardinality warning with an odd number of elements. #1668