VISION (and maintainer nodes):

add a trigger for reindexing to all neccessary places:
- when question gets deleted (list view AND pageview!?)
- when question gets added at certain position? should already cause reindexing
- for tests having participant data the sequences needs to be unserialized fixed from gaps and stored again.

- restoring sequences should actually happen in a normalized way (additional tables)

-> This would require to unserialize EVERY test sequence (every participant in every test)
to be unserialized, so migrating the storage is done for all data.
fixing the sequence is neccessary only for the test with question sets having position index gaps.

-> restoring the fixed sequences only, but in the current way -
serialized value in a single field -
will also deal with many many data, when the installation is accordingly large.
In both cases for many installations the migration will take a long time.

The gap issue is built in since many releases, so i guess it doesn matter if we take a long time
for migration or a longer time. Just for a few cases i think we would have a significant difference
that justifies to only migrate broken things prior to improve things.

The general fix to avoid more tests from geting broken will be implemented in the close future of course,
the migration will take some more time.