fixup! Upgrade Argument Parser to 1.1.0

Add Slack Integration For GH Action

Remove Travis CI

Eliminate compiler warning

Swift 5.2 surfaces this unused variable `v` during compilation. Let's
get rid of the warning.

Make classes final

Gardening, NFC.

Switch to apple/swift-tools-support-core

… as opposed to using SwiftPM directly. This is way of the future.

Update SwiftPM instruction in README

Declare a FileCheck Tool

Merge pull request #12 from llvm-swift/update

Update to Swift 5

Merge pull request #9 from llvm-swift/touch-up

Build with Xcode 10

Resolve ASAN issues