supporting DMD-1.016 and DMD-2.000 with the same source code

[Daniel Keep]

Sean Kelly wrote:
> Thomas Kuehne wrote:
>>
>> 4) class invariants
>> ===================
>>
>> This is the only real trouble spot so far. DMD-1 uses
>>     invariant{ ... assert(...); ... }
>> however DMD-2 uses
>>     invariant(){ ... assert(...); ... }
> 
> Well that's unfortunate.  I don't suppose unittest has gotten
> parenthesis as well?
> 
> 
> Sean

I suspect this is because invariant is now a declaration, a storage
class *and* a type constructor.

	-- Daniel