[SR-511] SE-011: Add "associatedtype" keyword for declaring associated types

[DougGregor]

Previous ID	SR-511
Radar	rdar://problem/24159196
Original Reporter	@DougGregor
Type	Bug
Status	Closed
Resolution	Done

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug
Assignee	@gregomni
Priority	Medium

md5: c05adde51e333cbc869be19170ae860f

Issue Description:

Per

https://github.com/apple/swift-evolution/blob/master/proposals/0011-replace-typealias-associated.md

we need to add the "associatedtype" keyword to declare associated types. In addition, we should add a warning + Fix-It that replaces "typealias" with "associatedtype".

[lattner]

It would be great to get the warning/migration in for Swift 2.2.

[gregomni]

Mostly complete pull request at <https://github.com/apple/swift/pull/964\>. Still would like some input on what to do when "associatedtype" is attempted outside of a protocol.