Struct initialization, implicit conversions and delegates

[Trass3r]

> StringHash sh = "SomeString"; // ok

That's the only thing that works.
An @implicit tag for constructors to allow all implicit conversions would  
really be helpful.

In general we need finer control of implicit conversions.
Just have a look at ProxyOf:  
https://github.com/D-Programming-Language/phobos/pull/300/files#L0R2670

That's madness, all of that code just for getting alias this without  
implicit conversion to the original type.