add toString to TypedProgram

src/main/java/de/maishai/typedast/typedclass/TypedProgram.java

@@ -73,4 +73,12 @@ public class TypedProgram {
             return false;
         }
     }
+
+    @Override
+    public String toString() {
+        return "TypedProgram{" +
+                "typedClasses=" + typedClasses +
+                ", currentClass=" + currentClass +
+                '}';
+    }
 }