UI HANG

- Made it Exceedingly hard to mine on a low-diff fork in prod (.001%) -
Diff must be > .40 - Note this only stops established forks, And made it
exceedingly hard to stake when out of sync
- Fixed GetNumBlocksOfPeers for IsInitialDownload and used it for Blocks
Estimate
- Made grandfather block dynamic for faster initial sync
- Added execute unfork command, this resets the chain 50 blocks prior to
the best block - Please test
- Prevented UI hang in 8.1