Added reduce method to EquaSet.
Added reduceLeft to EquaSet.
Added reduceLeftOption to EquaSet.
Added reduceOption method to EquaSet.
Added reduceRight method to EquaSet.
Added reduceRightOption method to EquaSet.
Added repr method to EquaSet.
Add toList to EquaSet and SortedEquaSet implementation to preserve the order of underlying set.
Added slice method to EquaSet.
Added 2 sliding methods to EquaSet.
Added span method to EquaSet.
Added splitAt method to EquaSet.
Added stringPrefix method to EquaSet.
Make FastEquaSet and TreeEquaSet to use prefixString in their toString implementation.
Added subsetOf method to EquaSet.
Added 2 subsets method to EquaSet.
Added sum method to EquaSet.
Added tail method to EquaSet.
Added tails method to EquaSet.
Added take method to EquaSet.