Topic/accumulate tests in hierarchies

Ensure that all tests are executed in code like this:
```scala
class A extends PerformanceTest {
  //some tests
}
class B extends A {
 //other tests
}
```

In the above code, `delayedInit` is called twice:

```scala
class A extends DelayedInit {
  def delayedInit(body: => Unit) {
    println("delayedInit START")
    body
    println("delayedInit END")
  }
  println("A's constructor!")
}
class B extends A {
  println("B's constructor!")
}
```

REPL interaction for the above minimal test:
```
scala> new B
delayedInit START
A's constructor!
delayedInit END
delayedInit START
B's constructor!
delayedInit END
```

I verified this behavior in 2.10.2, and it seems to agree with a careful reading of the specification and documentation of `DelayedInit`, since both `A` and `B` inherit from `DelayedInit` hence their constructors are both transformed.