Class inheritance bug

[Tobias M.]

I did not want to use threads for mutile sockets. I wanted to have the main thread
prompting the user for input with readln() and a new thread listening for incoming
messages and printing them with writeln(). But ill have to see if that actually works.

The problem here is not Threads but that whenever i extend a class i can´t compile
my code. The OOP in D is simpy unneccesary and absolete if i can´t create
subclasses. This has to be fixed.
In the cases where a class does not need to be extended it could be declared as
final but that would be out-of-scope and topic.