organize writers hierarchy

src/main/java/kieker/analysis/graph/export/AbstractTransformer.java

@@ -20,8 +20,12 @@ public abstract class AbstractTransformer<O> implements VertexVisitor, EdgeVisit
 
 	public final O transform() {
 
+		// Call startTransformation()
+
 		graphTraverser.traverse(graph);
 
+		// Call finishTransformation()
+
 		return getTransformation();
 	}
 

src/main/java/kieker/analysis/graph/export/AbstractWriter.java

@@ -8,7 +8,6 @@ public abstract class AbstractWriter extends AbstractTransformer<Void> {
 
 	protected AbstractWriter(final Graph graph) {
 		super(graph);
-		start();
 	}
 
 	@Override