* liquidator: forcefully exit process if snapshot job die
* client: return snapshot_job join handle so it can be watched for early unexpected exit
(cherry picked from commit 2520c7d095)
- Don't just restart on new listings, but also on significant changes to
old listings such as oracle changes.
- Cover the liquidator and settler in addition to the keeper.
microwavedcola1
Serge Farny
Christian Kamm