Provide synchronized date format implementation
Provide constance for common date formats, i. e. ISO8601
Add facade class for Comparators

Comparators class provides naturalOrder method.
Natural order is a Comparator wich use is analogues to using compareTo method of Comparable interface.
Rename CloseableFluentIteratorImplementation to IteratorCloseableFluentIterator

Try to avoid Implementation word in class names
Add join method for Strings
Follow closeally to collection API

Do not introduce new strongly-typed methods.
Use runtime type-checks to implement correct behaviour instead.
Revert back to common/mathematical type-arguments order

Revert back type-argument order for Function interface and alike.
Function<T, R> now means a function from T to R.
Function<T, R> argument type is T.
Function<T, R> result type is R.