todo statement, -beta and -airy compiler options

[Reiner Pope]

Manfred Nowak wrote:
> It seems common practice to put a hint to not yet implemented code in 
> a comment starting with "TODO" or similar wording.
> 
> Therefore I believe that compiler assistance for this behaviour 
> should be available.
> 
> The language allows for a `todo' statement, which may be a keyword-
> only  statement or similar to a line comment starting with keyword 
> `todo'.

Nice idea. How about

    pragma(todo, "Message");



    -- Reiner