Xcode 9.3 and Swift 4.1 Support

Released on 2018-04-10. All issues associated with this milestone can be found using this filter.

Updated

• The Xcode project to support Xcode 9.3.
  • Updated by Colby Williams in Pull Request #38.
• The Travis-CI YAML file to support Xcode 9.3.
  • Updated by Christian Noon in Pull Request #39.

Fixed

• Compiler warnings in the test suite on Xcode 9.3 for the characters property on String.
  • Fixed by Christian Noon in Pull Request #39.