Upgrade to Swift 5 (#224) * Upgrade to Swift 5 - Fix test target - Upgrade everything to Swift 5 - Fix compiler warnings - Small refactor in VideoScrubber to DRY up code and fix warnings - Update .travis.yml for Xcode 11 - Remove obsolete .swift-version file - Bump version to 6.0.0 * Fix .travis.yml to use iPhone 11 simulator