rvalue references

[Namespace via Digitalmars-d]

> 3. Add a new attribute - e.g. @rvalue ref - which inserts a 
> temporary variable for rvalues so that they can be passed by 
> ref, and it works with both templated and non-templated 
> functions.

We could also somehow use 'return ref' for that purpose, or we 
could get rid of the pointless 'const scope' alias 'in' and use 
'in ref' as a new attribute. But somehow I would prefer 'auto 
ref', it's a more descriptive term.