Fixed gemspec.

Some file names have changed.
Restoring version correctly.
Changed deleted_in_original_table from boolean to integer.

But it would be better to have a record_restored field, since
deleted_in_original_table is used as boolean everywhere in the
TISS code (as well as in the tiss_test code). Plus migrations
would be more easy.
Fixes #5611: record_restored flag for versioned tables.

record_restored is set in the version record that gets restored
(but not in the version record that is created upon restore).

Migration neccessary.
Merge branch 't5611-deleted-in-original-table-2-bei-restore'
Fixes #5611: Record restored now only set in the record created upon restore.
Merge branch 't5611-deleted-in-original-table-2-bei-restore'
Merge branch 'master' into experimenting-with-optimistic-locking