* Obsolete ModifierSlice typealiases in 5.0
* Obsolete *Indexable in 5.0
* Obsolete IteratorOverOne/EmptyIterator in 5.0
* Obsolete lazy typealiases in 5.0
* Drop .characters from tests
* Obsolete old literal protocols in 5.0
* Obsolete Range conversion helpers in 5.0
* Obsolete IndexDistance helpers in 5.0
* Obsolete Unsafe compat helpers in 5.0
* Obsolete flatMap compatibility helper in 5.0
* Obsolete withMutableCharacters in 5.0
* Obsolete customPlaygroundQuickLook in 5.0
* Deprecate Zip2Sequence streams in 5.0
* Replace * with swift on lotsa stuff
* Back off obsoleting playground conformances for now
This converts the instances of the pattern for which we have a proper
substitution in lit. This will make it easier to replace it
appropriately with Windows equivalents.
* [stdlib] Backward compatibility fix for a flatMap on [String]
Since String started to conform to Collection, the flatMap with a
sequence returning closure is now a better match that the one that
relies on the optional promotion in this code:
[""].flatMap { $0 }
which results in the default type of this expression changing from
[String] to [Character].
Restoring the old behavior in Swift 3 mode by adding a very explicit
overload.
Fixes: <rdar://problem/32024978>
* [stdlib] Fixing another compatibility issue with [String].flatMap
