Major Description
These are various improvements/fixes needed for issues discovered during testing with incremental policy/delta enabled.
Highlights:
1. Threads are named for better debugging information.
2. super.join() call is made in a loop to ensure that thread is really terminated even in the face of spurious/out-of-sync interruptions.
3. preCleanup() call ensures that clean-up happens at least and exactly once, when incremental policy/tag feature is enabled.