Save example script output to files

[einbandi]

In order to make the docs future-safe, rewrite the scripts in such a way that the output images of plots and the logs are written to files, which the docs can simply include. For logs, this issue is related to #34, for images to #39.

[einbandi]

This works now, as indicated in the old example scripts. But after changing the examples to notebooks, this issue is no longer relevant anyway.