Remove unused 'release' method on TT data sets
Add isolation group IDs to TT data sets.
Generate isolated data sets from the crossfold task
Isolate data sets in different groups
Improve caching of specialized DAOs in evaluator

- Introduce common wrapping/cache logic for prefetching DAOs
- Use soft memoization for wrapper DAOs
- Retain event DAO reference in external eval job
set encoding for JavaDoc
Fix typos & stuff
Merge branch 'feature/elehack-eval-ds-cleanup'