v1.27.0

Added

• Sankey diagram with new trace type sankey [#1591, #1664]
• Add hoverlabel trace and layout attributes to customize hover label colors
  and fonts [#1582]
• Add marker.gradient attributes for scatter, scattergeo, scatterternary
  and scattercarpet traces [#1620]
• Add sort transform [#1609]
• Add preservegaps filter transform attribute [#1589]
• Add != (not equal) filter transform operation [#1589]
• Add labelfont, tickfont and rangefont attributes for parcoords traces
  [#1624]
• Pass DOM mouse event on plotly_clickannotations events [#1652]

Changed

• Performance optimization for range sliders and Drawing cache [#1585]

Fixed

• Fix scattergl marker symbol positioning (bug introduced in 1.25.0) [#1633]
• Fix gl2d zoom where two clicks would trigger a zoom box (bug introduced 1.26.0) [#1632]
• Fix legend double click handler for carpet traces [#1636]
• Fix restyle for scattercarpet for style attributes with array support [#1641]
• Fix restyle for array layout components when more than 10 items are present
  [#1639]
• Fix select-box and lasso selections so that they don't include bad-data items
  [#1656]
• Fix restyle for contour zmin and zmax [#1653]
• Fix scatter text node transitions [#1616, #1626]