Refactor proof of work related functions out of main

src/main.h

@@ -146,10 +146,6 @@ bool ProcessMessages(CNode* pfrom);
 bool SendMessages(CNode* pto, bool fSendTrickle);
 /** Run an instance of the script checking thread */
 void ThreadScriptCheck();
-/** Check whether a block hash satisfies the proof-of-work requirement specified by nBits */
-bool CheckProofOfWork(uint256 hash, unsigned int nBits);
-/** Calculate the minimum amount of work a received block needs, without knowing its direct parent */
-unsigned int ComputeMinWork(unsigned int nBase, int64_t nTime);
 /** Check whether we are doing an initial block download (synchronizing from disk or network) */
 bool IsInitialBlockDownload();
 /** Format a string that describes several potential problems detected by the core */
@@ -159,7 +155,6 @@ bool GetTransaction(const uint256 &hash, CTransaction &tx, uint256 &hashBlock, b
 /** Find the best known block, and make it the tip of the block chain */
 bool ActivateBestChain(CValidationState &state);
 int64_t GetBlockValue(int nHeight, int64_t nFees);
-unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock);
 
 void UpdateTime(CBlockHeader& block, const CBlockIndex* pindexPrev);
 
@@ -812,11 +807,6 @@ public:
         return (~bnTarget / (bnTarget + 1)) + 1;
     }
 
-    bool CheckIndex() const
-    {
-        return CheckProofOfWork(GetBlockHash(), nBits);
-    }
-
     enum { nMedianTimeSpan=11 };
 
     int64_t GetMedianTimePast() const