7 new utilities

Added

• Generators
  • iter.create.from() for creating iterators from functions.
  • iter.create.constant() for creating an endless iterable of the same value.
  • iter.create.randomNumbers() for creating an endless iterable of
    pseudorandom numbers.
• Transformers
  • iter.map() (like Array.prototype.map)
  • iter.take() for taking the first n items of an iterable.
• Combinators
  • iter.pair() for zipping two iterables.
  • iter.concat (like Array.prototype.concat)