Some minor improvements

(Get rid of IPlanner property on ReadOnlyKernel, Made NinjectSettings clonable, BindingPrecedenceComparer gets injected in ReadOnlyKernel)
Removed ISelector from ReadonlyKernel
Merge branch '4.0.0' of https://github.com/iappert/ninject into 4.0.0

Conflicts:
	src/Ninject/Activation/Context.cs
	src/Ninject/Activation/Providers/StandardProvider.cs
	src/Ninject/BindingPrecedenceComparer.cs
	src/Ninject/IBindingPrecedenceComparer.cs
	src/Ninject/IReadonlyKernel.cs
	src/Ninject/KernelBase.cs
	src/Ninject/ReadonlyKernel.cs