Changelog of @hackage/hgg-core 0.2.0.0

Changelog for `hgg-core`

Breaking: theme constructors ThemeCanvas / ThemeCanvasDark renamed to ThemeParchment / ThemeParchmentDark.
Generalized coordinate systems: ternary coordinates (ternaryScatter / ternaryLine marks, encZ channel), polar start angle / direction / rotation, polygon clipping; crossbar renders through the projection layer (correct in polar coordinates).
Theme extensions (cowplot parity): base-size scaling, font family, plot margins, subplot relative widths and tags, three new presets; grid and axis line widths are now theme-controlled.
Fixes: facets now split inline (non-DataFrame) layer data; boxplot outliers are included in the axis domain.
Bilingual (English / Japanese) haddock across the public API.

First public release on Hackage.

Backend-independent core: VisualSpec / layers / marks / encoding / scales / themes.
Depends only on base / vector / text / containers.