Support "key in map" using extension contains() function. #KT-3607 Fixed
Fix String.dropWhile & String.takeWhile
Stream.filterIsInstance has wrong return type #KT-5097 Fixed
Support generating "deprecated" functions.
Created join, joinTo and joinToString functions, deprecated makeString & appendString #KT-3841 Fixed
Migrate to using join* functions instead of deprecated.
Improve iterators' functions deprecation text
Convert iterable of pairs to map, improve generic toMap(mutableMap) function #KT-4166 Fixed