[Types-sig] Type annotations

[Tim Peters]

[Paul]
> 3. in separate decl statements: (Incompatible with Python 1.5, but
> easily converted)
> 
>   Python 1.5 compatibility: low

Noting that

    decl x: Int

could just as well be spelled

    # decl x: Int

That would knock it down on the "syntactic cleanliness" scale, though!