message: Increase miners' default maximum block weight and size
diff: class CCoinsViewCache;
  /** Default for -blockmaxsize, which controls the maximum size of block the mining code will create **/
  -static const unsigned int DEFAULT_BLOCK_MAX_SIZE = 750000;
  +static const unsigned int DEFAULT_BLOCK_MAX_SIZE = 1900000;
  /** Default for -blockprioritysize, maximum space for zero/low-fee transactions **/
  static const unsigned int DEFAULT_BLOCK_PRIORITY_SIZE = 0;
  /** Default for -blockmaxweight, which controls the range of block weights the mining code will create **/
  -static const unsigned int DEFAULT_BLOCK_MAX_WEIGHT = 3000000;
  +static const unsigned int DEFAULT_BLOCK_MAX_WEIGHT = 7600000;
  /** Default for -blockmintxfee, which sets the minimum feerate for a transaction in blocks created by mining code **/
  static const unsigned int DEFAULT_BLOCK_MIN_TX_FEE = 1000;
  /** The maximum weight for transactions we're willing to relay/mine */
  