NewLines should not be stored in the DB as they never get deleted

### Removed the saving of DocumentLine to the DB.

The DocumentLine were previously stored in the DB as an own collection. 

However the DocumentLine were also stored in the document (where they actually belong to).

As an DocumentLine collection does not have any connection with an document if they are stored as an collection in the DB they were also never deleted. To avoid to get a DB full of DocumentLine entries, I switched of the storage of them.