Migration task

We've changed the database model for the following reasons:

• Tables were limited to 2 billion records, which was a (distant but uncertain) risk because each requirement can have dozens of properties, saved several times for hundreds of baselines. Our new tables support IDs up to 9,223,372,036,854,775,807 (inclusive).
• We've greatly improved the tracking of dependencies across baselines. We are extremely proud of this, hoping that the new behaviour will be invisible to the untrained eye.
• We've made it possible to add external properties to requirements, which we are demonstrating with the "Estimates" feature, and which we are going to expand with other features in the future.

Therefore, it was necessary to transfer all data from the older to the newer tables.