On exceptions, errors, and contract violations

[Dicebot via Digitalmars-d]

I agree with most parts and this pretty much fits my unhappy 
experience of trying to use D assert/contract system. However I 
don't feel like contracts and plain assertions should throw 
different kinds of exceptions - it allows to distinguish some 
cases but does not solve the problem in general. And those are 
essentially the same tools so having same exception types make 
sense.

Different compilation versions sound more suitable but that 
creates usual distribution problems with exponential version 
explosion.