Allow identical imports

[Dicebot]

On Tuesday, 30 July 2013 at 14:52:52 UTC, Tofu Ninja wrote:
> I would think that a redundant import would be something along 
> the lines of a warning, not a full on error, there is no reason 
> the compiler shouldn't be able to compile it.

That is somewhat similar to "statement has no effect" error. Any 
warning that has no valid use case should be an error, it does 
not matter if compiler can do it.