Implemented query functions
Implemented `insert` and `delete`
Implemented combine functions
Documentation for `splitLookup` fixed
Implemented `map`
Implemented fold functions
Implemented min/max functions
Implemented elems
Implemented ordered list functions
Lifts replaced by wraps
Implemented `keysSet`
Implemented `fromSet`
Merge pull request #71 from kgeorgiy/set

Implemented functions in Set