* Use correct release for getblocktemplate config
* Include at least 2 full checkpoints in the lookahead limit
* Increase full sync timeout to 36 hours
* Only log "synced block height too far ahead of the tip" once
* Replace AboveLookaheadHeightLimit error with pausing the syncer
* Use AboveLookaheadHeightLimit for blocks a very long way from the tip
* Also add the getblocktemplate config, and fix the test message
* Remove an outdated TODO comment
* Allow syncing again when a small number of blocks are in the queue
* Allow some dead code