v0.2.4

Added

• Implemented Amount.AddMul, Amount.AddQuo, Amount.SubMul, Amount.SubQuo, Amount.Equal, Amount.Less.

• Implemented Currency.AppendBinary, Currency.AppendText, Currency.UnmarshalJSON, Currency.MarshalJSON, Currency.UnmarshalBSONValue, Currency.MarshalBSONValue.

Changed

• ExchangeRate.Conv supports both direct and reverse conversions.
• Deprecated Amount.FMA and ExchangeRate.Inv methods.