ModbusMaster use deprecated methods

[leoandrea7]

Hi, I noticed that in ModbusMaster.java are used deprecated methods. Indeed inside readHoldingRegisters and readInputRegisters methods the return value is given by response.getRegisters() ​that is deprecated. Maybe the right return value should be response.getHoldingRegister(), in this way is possible to use convert methods of ModbusHoldingRegisters.class.

The same goes for readCoils and readDiscreteInputs methods. Thanks.