set6 0.2.0

• UniversalSet renamed Universal, old class will be removed in v0.4.0.
• LogicalSet renamed Logicals, old class will be removed in v0.4.0.
• Complex now inherits from Set, incorrect methods for isSubset, equals have been removed.
• Add Multiset for sets with non-unique elements but no ordering
• Small speed improvements in Tuple and FuzzyTuple
• For consistency most methods now return a list unless single elements requested
• Printing of ConditionalSet is fixed
• Rationals and child-classes now error on calls to contains, isSubset, equals as any prior results were likely wrong/misleading
• Removed erroneous complex boundaries in Interval class