message: initialize uint256 to null
diff: @@ -132,7 +132,7 @@ public:
  class uint256 : public base_blob<256>
  {
  public:
  - uint256() {}
  + uint256() : base_blob<256>() {}
  uint256(const base_blob<256> &b) : base_blob<256>(b) {}
  explicit uint256(const std::vector<unsigned char> &vch) : base_blob<256>(vch) {}
  /** A cheap hash function that just returns 64 bits from the result, it can be
  