message: Fix bug in key encoder for class B
diff: @@ -68,20 +68,21 @@ public:
  }
  std::array<unsigned char, CPubKey::COMPRESSED_PUBLIC_KEY_SIZE> data = {}; // Zeroes all bytes.
  - auto it = data.begin();
  // Write chunk number and payload.
  static_assert(CLASS_B_CHUNK_SIZE + 2 == CPubKey::COMPRESSED_PUBLIC_KEY_SIZE, "Chunk size is not in the expected size");
  static_assert(CLASS_B_CHUNK_PAYLOAD_SIZE + 1 == CLASS_B_CHUNK_SIZE, "Payload size is not in the expected size");
  - *it++ = 0x02; // Compressed public key indicator.
  - *it++ = chunk;
  + data[0] = 0x02; // Compressed public key indicator.
  + data[1] = chunk;
  - std::copy(first, last, it);
  + std::copy(first, last, data.begin() + 2);
  // Obfuscation packet, which is chunk number and payload.
  static_assert(std::tuple_size<decltype(encKey)>::value == CLASS_B_CHUNK_SIZE, "Size of encryption key must be the same as chunk size");
  + auto it = data.begin() + 1;
  +
  for (unsigned i = 0; i < CLASS_B_CHUNK_SIZE; i++) {
  *it++ ^= encKey[i];
  }
  