Rationalise diffs stored in the work struct and document them to avoid further confusion
Merge pull request #588 from kanoi/min

Minion Updates
Merge pull request #589 from kanoi/master

minion - roll work to reduce CPU
Merge pull request #590 from kanoi/master

minion - comment out HW debug message
Work stats should be based on device_diff not work_difficulty since non-shares haven't been filtered out yet