0.6.0

• Comparison methods use Explanations instead of ContextRegisters
• Remove io/anchors module
• Remove "factors" module that conflicted with Nettlesome module of same name
• Add Fact.negated method
• Remove "role" param for Procedure.add_factor
• Rules can be added even if one of the operands has more Enactments
• Procedure.recursive_terms doesn't include FactorGroups
• Procedure.terms doesn't include FactorGroups
• Add comparable_with methods
• Decision is no longer a dataclass
• remove context param from Opinion comparisons
• handle Opinion.explanations_implication(HoldingGroup)
• Increase minimum Nettlesome version to 0.5.0