Restore Quark proof-of-work mining

src/primitives/block.cpp

@@ -15,10 +15,7 @@
 
 uint256 CBlockHeader::GetHash() const
 {
-    if(nVersion < 4)
-        return HashQuark(BEGIN(nVersion), END(nNonce));
-
-    return Hash(BEGIN(nVersion), END(nAccumulatorCheckpoint));
+    return HashQuark(BEGIN(nVersion), END(nNonce));
 }
 
 uint256 CBlock::BuildMerkleTree(bool* fMutated) const

src/rpc/mining.cpp

@@ -605,6 +605,7 @@ UniValue getblocktemplate(const UniValue& params, bool fHelp)
     result.push_back(Pair("curtime", pblock->GetBlockTime()));
     result.push_back(Pair("bits", strprintf("%08x", pblock->nBits)));
     result.push_back(Pair("height", (int64_t)(pindexPrev->nHeight + 1)));
+    result.push_back(Pair("acc_checkpoint", pblock->nAccumulatorCheckpoint.GetHex()));
     result.push_back(Pair("votes", aVotes));