Vega:

• Add CountPattern transform.
• Facet transform no longer requires a "groupby" directive.
• Add interactivity to Force transform.
• Add Lookup transform.
• Add Wordcloud transform.
• Add Voronoi transform.
• Deprecate Zip transform. (Use Lookup instead.)
• Add locale formatting support (via datalib 1.4.3)
• Add "open" expression function for hyperlinking.
• Refine schema and test cases.
• Miscellaneous bug fixes.

Vega Editor:

• Add airports, force_drag and wordcloud examples.
• Modify choropleth and force examples to use lookup transform.