DIP53 and DIP49 (ver2) - New definitions for qualified constructors and postblits

[bearophile]

Kenji Hara:

> I think adding new keyword/attribute just for readability is 
> overkill.

Making the code more explicit and easy to understand, using the 
right words, is rather important. So I like @unique, that can 
probably be re-uses for another purpose.

What's worse than having many keywords is having them with 
multiple meanings. Otherwise are you willing to explain again and 
again to future people in D.learn that specific "const" doesn't 
really mean const, it really means... and so on :-)

Bye,
bearophile