Add additional units

[nnichols]

Proposed Changes

• Added
  • brewtility.units.alcohol-content for converting and displaying alcohol content.
  • brewtility.units.bitterness for rendering displayable IBU values.
  • brewtility.units.carbonation for rendering displayable carbonation values.
  • brewtility.units.specific-gravity now supports measurements in degrees plato.
  • brewtility.predicates.options for option map keys shared across predicate namespaces.
• Changed
  • brewtility.units now supports a :precision option map key for all conversion functions. This key will round the converted value to the specified number of decimal places. Defaults to the precision of the converted value.
  • brewtility.units.color now supports a reverse-lookup for known RGBa values.
  • All functions in brewtility.predicates now support an option map as a second argument to make their arities consistent.
• Removed
  • ^:const metadata has been removed from conversion maps

Pre-merge Checklist

• Read and agree to the Contribution Guidelines and Code of Conduct
• Write new tests for the changed functionality
• Update CHANGELOG and increment version
• Update README and relevant documentation