0.18.0: Cat's Out Of The Bag

Breaking

• Xcode 8.3 or later and Swift 3.1 or later are required to build.
  Norio Nomura

Enhancements

• Cache NSString.CacheContainer on Linux, matching behavior on Darwin,
  speeding up many repeated operations on NSString on Linux.
  JP Simard
  realm/SwiftLint#1577

• Process Swift 3.2/4 doc comments.
  John Fairhurst

• Support building with Xcode 9 beta 3 and the latest Swift 4 snapshots.
  JP Simard

Bug Fixes

• None.