Changes from v5.9.0:

vega

• Fix rollup script to resolve symlinks.

vega-encode

• Fix log scale legend values and format. (#2290)

vega-projection-extended

• Fix rollup script to resolve symlinks.

vega-regression

• Update vega-statistics dependency.

vega-statistics

• Fix r-squared calculation for poly and quad regression. (Thanks @jakevdp!)

vega-time

• Fix time floor step bug, add tests. (#2270)

vega-util

• Fix splitAccessPath escape handling, add tests. (#2287)