v0.21.0

Breaking changes:

• The undocumented io.experimental.findAndSelectUser IO method has been
  removed in favor of the more powerful io.search

New:

• IO methods can now be conditionally marked as optional by providing a boolean
  value to optional()
• Action names and descriptions can now be defined in code
• Strings can be used as options directly in
  io.select.single and io.select.multiple
• Table columns definitions can now be arrays of string property names, allowing a subset of columns to be displayed without needing to use the more verbose column definitions syntax in
  io.display.table and io.select.table

Fixed:

• TypeScript will now properly indicate when an IO method call requires a
  properties argument (for example io.display.table) Thanks to Petr for reporting this bug!