Relink Database for scenario import

[marc-vdm]

When exchanging databases and scenarios with other users, database names may be changed by the user importing the data. The re-link database feature is really useful, but when loading scenario files, the database names cannot be changed. It would be nice if AB checks the databases in the scenario file and allows the user to re-link these.

AB could do the following:

1. Check all unique names in the from database and to database columns.
2. Assuming user chooses to relink:
3. AB changes all matching rows entries for that databases for columns from/to database and from/to key.

I'm not sure Pandas has a fast search/replace function for the to/from key as we need to change part of a tuple, not the full cell. Or that we would need to write something custom for this that iterates over each row and checks/replaces the database name.