Implement limits for distribution packages

In order to prevent the system from consuming too much resources when building or importing vault packages, it should be possible to limit the "transaction" size. This change in semantic should be easily possible, because there is not documented semantic, but always only best effort.

It should be possible to limit both the number of paths and the the overall size of the created vault packages. Of course the distribution should not block if a single (serialized) path exceeds the configured size limit, but in that case it should print a huge warning in the log.