Add "standard library" of helper functions

[Kacarott]

• [en/de]coders for a variety of encodings
• type constructors
• combinators

Importable, or in some way modularised (LC.helpers?)

[JohanWiltink]

• combinators
• datatypes: unit, booleans, ordering, lists, n-tuples ( probably in various encodings ) with various helpers
• instances for standard number encodings: Enum ( succ, pred ), Ord ( compare, lt, le, eq, ge, gt, min, max ), Num ( +, -, *, /, %, ^, gcd, lcm ), Bits ( shift, and, or, xor, test, popCount, clz, ctz, even, odd )
• BigInt, IEEE.754, BigNum - in exponentially increasing order of unlikeliness

[JohanWiltink]

Showcasing stuff in example kata is enough for now. copy-paste works just fine for a lot of folks. Also, without namespacing or renaming imports, resolving name clashes can only be done in a monolithic sourcefile.