undefined reference to "main"

[Alexander Zhirov]

How to compile the example given in the book correctly? When 
compiling, an error occurs that the main function is missing. If 
I replace `shared static this()` with `void main()', then 
everything starts. What does the compilation string in `dub` and 
`dmd` look like correctly?

```d
import vibe.d;

shared static this()
{
   auto settings = new HTTPServerSettings;
   settings.port = 8080;
   settings.bindAddresses = ["::1", "127.0.0.1"];
   listenHTTP(settings, &hello);

   logInfo("Please open http://127.0.0.1:8080/ in your browser.");
}

void hello(HTTPServerRequest req, HTTPServerResponse res)
{
   res.writeBody("Hello, World!");
}
```