forcing not written in directory specified by dir argument

When I run the makkink forcing and specify a directory that directory is used as the starting point for ESMValTool, but the final result is not written in that directory. This means that the result (including the yaml file with the forcing info) is written a few directories deeper. This means that

```python
forcing.sources["LumpedMakkingForcing"].generate(dir = "myDir")
```

followed by

```python
forcing = forcing.sources["LumpedMakkinkForcing"].load("myDir")
```

does not work, but should be

```python
forcing = forcing.sources["LumpedMakkinkForcing"].load("myDir" + "work/diagnostic/script")
```

to make it work. This is not consistent between forcing sources.