Update Equihash hash generation to match the Zcash spec

Changes:

- floor(512/n)*n/8 bytes of BLAKE2b output is split between floor(512/n)
  adjacent indices, instead of using one hash call per index.

- Parameters with n/(k+1) mod 8 != 0 will expand the BLAKE2b output to byte
  boundaries for colliding, instead of using a longer output and clearing bits.

- The genesis blocks have been regenerated.

- The test vectors have been regenerated.

- The Equihash inputs for the cancellation tests were modified to ensure that
  valid solutions were available to exercise the full solver.

src/crypto/equihash.h

@@ -45,8 +45,8 @@ protected:
     unsigned char hash[WIDTH];
 
 public:
-    StepRow(const eh_HashState& base_state, eh_index i,
-            size_t hLen, size_t cBitLen, size_t cByteLen);
+    StepRow(const unsigned char* hashIn, size_t hInLen,
+            size_t hLen, size_t cBitLen);
     ~StepRow() { }
 
     template<size_t W>
@@ -83,8 +83,8 @@ class FullStepRow : public StepRow<WIDTH>
     using StepRow<WIDTH>::hash;
 
 public:
-    FullStepRow(const eh_HashState& base_state, eh_index i,
-                size_t hLen, size_t cBitLen, size_t cByteLen);
+    FullStepRow(const unsigned char* hashIn, size_t hInLen,
+                size_t hLen, size_t cBitLen, eh_index i);
     ~FullStepRow() { }
 
     FullStepRow(const FullStepRow<WIDTH>& a) : StepRow<WIDTH> {a} { }
@@ -108,9 +108,9 @@ class TruncatedStepRow : public StepRow<WIDTH>
     using StepRow<WIDTH>::hash;
 
 public:
-    TruncatedStepRow(const eh_HashState& base_state, eh_index i,
-                     size_t hLen, size_t cBitLen, size_t cByteLen,
-                     unsigned int ilen);
+    TruncatedStepRow(const unsigned char* hashIn, size_t hInLen,
+                     size_t hLen, size_t cBitLen,
+                     eh_index i, unsigned int ilen);
     ~TruncatedStepRow() { }
 
     TruncatedStepRow(const TruncatedStepRow<WIDTH>& a) : StepRow<WIDTH> {a} { }
@@ -155,7 +155,9 @@ private:
     BOOST_STATIC_ASSERT((N/(K+1)) + 1 < 8*sizeof(eh_index));
 
 public:
-    enum { CollisionBitLength=N/(K+1) };
+    enum : size_t { IndicesPerHashOutput=512/N };
+    enum : size_t { HashOutput=IndicesPerHashOutput*N/8 };
+    enum : size_t { CollisionBitLength=N/(K+1) };
     enum : size_t { CollisionByteLength=(CollisionBitLength+7)/8 };
     enum : size_t { HashLength=(K+1)*CollisionByteLength };
     enum : size_t { FullWidth=2*CollisionByteLength+sizeof(eh_index)*(1 << (K-1)) };