hardhat 0.2.0

• Moved tune() from tune to hardhat (#181).

• Added extract_parameter_dials() and extract_parameter_set_dials() generics
  to extend the family of extract_*() generics.

• mold() no longer misinterprets :: as an interaction term (#174).

• When indicators = "none", mold() no longer misinterprets factor columns
  as being part of an inline function if there is a similarly named non-factor
  column also present (#182).