Build a multi-platform XCFramework for releases

Merge pull request #57 from tonyarnold/releases/1.4.3

Release version 1.4.3

Ensure that the project uses the latest CocoaPods prerelease to lint …

…the project

Update README and add support for CocoaPods’ new Swift version support

Merge pull request #50 from tonyarnold/swift-5.0

Xcode 10.2 and Swift 5.0 compatibility

Bump versions to v1.3.0

Bump version to 1.2.3

Bump to version 1.2.2