Separate integration of reporting from descriptors

[nils-christian]

Currently there is only one integration-aggregator containing both the reporting transformation (e.g., AsciiDoc) and the actual descriptors (e.g, jmolecules). If we start to write more integrations (#24, #25), we should probably separate those integration aspects.

[OLibutzki]

I agree. Honestly, I did not find good names to distinguish the modules, but it might make sense.

Anyway, due to the limited amount of time (not everyone is in vacations!) I'd like to focus on improving the API.

Such a refactoring can be done when things become too complex.

Until now it's quite manageable.