dump_Instance fails with NullPointerException

```
This code fails when "c" is null:

                for(content c: inst.annotations.get(cd)) {
                    sb.append("        ").append(c.toString()).append(linesep);
                }

Fixed that with: ...append(String.valueOf(c))...
```

Original issue reported on code.google.com by `alxfedo...@gmail.com` on 24 Jan 2013 at 4:36
