Version 3.2.0 (released August 5, 2019)

Upgraded to Vega-Lite version 3.4 (See Vega-Lite 3.4 Release Notes).

Following are changes to Altair in addition to those that came with VL 3.4:

Enhancements

• Selector values can be used directly in expressions (#1599)
• Top-level chart repr is now truncated to improve readability of error
  messages (#1572)

Bug Fixes

• top-level add_selection methods now delegate to sub-charts. Previously
  they produced invalid charts (#1607)
• Unsupported mark_*() methods removed from LayerChart (#1607)
• New encoding channels are properly parsed (#1597)
• Data context is propagated when encodings are specified as lists (#1587)

Backward-Incompatible Changes

• alt.LayerChart no longer has mark_*() methods, because they never
  produced valid chart specifications) (#1607)