Store the Equihash solution in minimal representation in the block header

The genesis blocks and miner tests have been regenerated, because changing the
block header serialisation format changes the block hash, and thus validity.

The Equihash solutions have been removed from the bloom test inputs for
simplicity (block validity is not checked there; only a valid serialisation is
necessary).

src/pow.cpp

@@ -96,6 +96,10 @@ unsigned int CalculateNextWorkRequired(uint32_t nBits, int64_t nLastBlockTime, i
 
 bool CheckEquihashSolution(const CBlockHeader *pblock, const CChainParams& params)
 {
+    // Don't validate genesis
+    if (pblock->hashPrevBlock.IsNull())
+        return true;
+
     unsigned int n = params.EquihashN();
     unsigned int k = params.EquihashK();