Auto merge of #1047 - aniemerg:fix/get-difficulty-fix2, r=ebfull
Auto merge of #1047 - aniemerg:fix/get-difficulty-fix2, r=ebfull

Update GetDifficulty() to use consensus.powLimit from consensus parameters.

Fixes #1032.

CTRoundTable/Encrypted.Cash,bitcoinsSG/zcash,CTRoundTable/Encrypted.Cash,CTRoundTable/Encrypted.Cash,CTRoundTable/Encrypted.Cash,bitcoinsSG/zcash,CTRoundTable/Encrypted.Cash,CTRoundTable/Encrypted.Cash,bitcoinsSG/zcash,bitcoinsSG/zcash,bitcoinsSG/zcash,bitcoinsSG/zcash