Integrate linter and code formatter in the build process

[wojciechczerski]

To ensure code format consistency we could use SwiftFormat. We can integrate it as a build phase that triggers a warning or an error if swiftformat command was not found. If we choose the error approach we should clearly describe in README that in order to contribute to the project you should first make sure you have the swiftformat installed.

In addition we could use SwiftLint to ensure a consistent code style. The integration options are the same as for the SwiftFormat.