State checking for extending abstract classes

Nobody has claimed this yet.

Currently, reusing state refinements from an abstract superclass in a concrete class is not fully implemented, and gives an error like the one below.

Example for abstract class `java.net.URLConnection`:
```java
@ExternalRefinementsFor("java.net.URLConnection")
@StateSet({"setup", "connected"})
public interface URLConnectionRefinements {

@StateRefinement(to="setup(this)")
public void URLConnection(URL url);

@StateRefinement(from="setup(this)")
public void setDoInput(boolean doinput);

@StateRefinement(from="setup(this)", to="connected(this)")
public void connect();

@StateRefinement(from="connected(this)")
public Object getContent();

}
```

Extended in class `URLExt`:
```java
class URLExt extends URLConnection{

public URLExt(URL url){
super(url);
}

@Override
public void connect() throws IOException {
// TODO Auto-generated method stub
throw new UnsupportedOperationException("Unimplemented method 'connect'");
}

}```

Tested in:
```java
class Testurl {
void test() throws URISyntaxException, IOException {

URLExt u = new URLExt(new URI("http://example.com").toURL());
u.setDoInput(false); // should not be an error but it is
u.getContent(); // should be an error

}
}
```

Reproduce the report using the URLConnectionRefinements annotations, URLExt, and Testurl example. Start by tracing how inherited state refinements from java.net.URLConnection are checked when methods are invoked on URLExt. Done means setDoInput(false) is accepted while getContent() is rejected because the object has not reached connected state.

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