Manually check all cores for reports after flush
Fix: Only one die was checked after flush in last commit

This is still a very crude way to handle a problem with lost works after
flushes, but already shows some promising results.
Do manual core checks in parallel with normal ones
Wrong variable used in new per-die iteration
Remove temporary log messages for manual report checks
Merge remote-tracking branch 'knc/titan-flush-optimize' into bfgminer
Bugfix: Extra garbage was sent on SPI with new commands
Init last_nonce on die reconfiguration to avoid lots of "unknown work" messages
Update knc-asic: Fix issue with detect_die crashing due to errors in response