split interfaces and implementation

[Lakritzator]

This should make it easier to maintain the dependencies, less changes.
I currently have Dapplo.Owin depend on Dapplo.Config just for IIniSection, which needs Dapplo.Utils and Dapplo.InterfaceImpl

[Lakritzator]

And Dapplo.Addons depends on Dapplo.Config, just for the IConfigProvider interface!

public interface IConfigProvider : IDisposable
  {
    object Get(Type type);
  }