Generic mixins for IMutableDependencyResolver register functions

[patsissons]

adding three generic mixins for Register, RegisterConstant, and RegisterLazySingleton. These mixins allow registration based on a generic type parameter rather than using typeof(...) as a serviceType parameter.

// Example usage
public class AppBootstrapper : ReactiveObject, IScreen
{
    public AppBootstrapper()
    {
        // old method
        // dependencyResolver.RegisterConstant(this, typeof(IScreen));

        // new method
        dependencyResolver.RegisterConstant<IScreen>(this);
    }
}

New mixin functions simply call their non-generic mixin counterparts, except for Register which is not a mixin to begin with.

[flagbug]

Would it make sense to check if the class actually implements the type parameter?

Something like

public static void Register<TInterface, TClass>(
    this IMutableDependencyResolver This, 
    Func<TClass> factory, string contract = null) 
    where TClass : TInterface
{
    This.Register(factory, typeof(TInterface), contract);
}

[kentcb]

@flagbug problem with that caller is required to specify both types rather than just one (or none in some cases).

locator.Register<ISomething>(() => new Something());

Versus:

locator.Register<ISomething, Something>(() => new Something());

Also, it doesn't add anything that can't be achieved by changing the lambda to Func<T> instead of Func<object>. I'm doing this in a branch at the moment and will submit PR shortly.

[kentcb]

Superseded by #128.