Autoboxing support

In situations where we have a containing element which has as its child a single container, we should make it easy to autobox it.

Example: 

choice ch {
  case foo-case {
    container foo {
      ...
    }

  }
}

foo-case contains a single container, foo. We should add an interface to Foo AutoBoxAble<FooCase>, and provide it a method

class Foo {
  ...

  public FooCase autoBox() {
   // wraps Foo in FooCase and returns it
  }
}
 

The same can also be done for containers:

container bar-container {
  container bar {
     ...
  }
}

public class Bar {
  public BarContainer autoBox();
}

 and lists

list baz-entry { container baz { ... } }

public class Baz { public BazEntry autoBox(); }

Note, this would be done only in the case where there was only where there is a single container child.