Changed Set::key() to yield position from start of set via new `SequentialKeyIterator` (#32)
Added test for workaround given in #34
Added SequentialKeyIterator to README.
Implement IterableInterface::partition(), each(), any() and all() (fixes #30, #37)

* LinkedList
* Map
* Set
* Vector
Updated type checks.
Updated changelog [ci skip]
Switched implementation detail methods to private and removed typhoon checks for performance.
Implemented utility functions (#27).
Added TraitsProviderInterface to IterableInterface (#39)
Updated to archer 0.2.1
Update README.md
Updated to archer 0.3.1
Updated to Archer v0.4.0
Minor documentation improvements.
Updated changelog style [ci skip]
Condensed the changelog slightly [ci skip]
Minor documentation improvements.
Added link to API docs to readme [ci skip]
Updated composer deps and readme.
Housekeeping.