Add Select method to IImplementationTypeFilter

[ajdean]

Made an attempt to "fix" #96, by adding a Select method to the IImplementationTypeFilter interface that then allows the matched types to be transformed. Can now register such types like so:

services.Scan(scan => scan.FromAssemblyOf<IBaseEntity>()
  .AddClasses(classes => classes.AssignableTo<IBaseEntity>().Select(type => typeof(GetOneByIdHandler<>).MakeGenericType(type)))
  .AsImplementedInterfaces());