Let's improve D's exceptions

[Jacob Carlborg via Digitalmars-d]

On 2015-05-14 03:31, Adam D. Ruppe wrote:

> Yeah, we could use a decent hierarchy too. Though the examples in there
> still use string concatenation to form the message, which is the big
> thing I want to get away from.

It was a while since I looked at that DIP, but I'm mostly interested in 
the hierarchy.

-- 
/Jacob Carlborg