Implicit instantiation of parameterless templates

[Piotr Szturmaj]

Java and C# with their generics can do the following:

class List { }
class List<T> { }

List list = new List();
List<int> intList = new List<int>();

In D similar code can't work because we can't have both a type and a 
template with the same name. So this code must be rewritten to:

class List(T = Variant) { }

List!() list = new List!();
List!int intList = new List!int;

When template name is used as a type and it can be instantiated with no 
parameters it could be automatically rewritten to List!() by the 
compiler. That code would then look like this:

List list = new List;
List!int intList = new List!int;

The question is... is it possible to change D's behaviour to avoid 
awkward !() template parameters _without_ breaking backward compatibility?