Porting code from v2.0 to v3.0

The table below presents a brief overview of changes that need to be applied to existing code in order to make it work with liblightmodbus v3.0.

Task	Changes
Slave init	Update call to modbusSlaveInit() according to Slave initialization.
Master init	Update call to modbusMasterInit() according to Master initialization.
Slave cleanup	Rename modbusSlaveEnd() to modbusSlaveDestroy()
Master cleanup	Rename modbusMasterEnd() to modbusMasterDestroy()
Error handling	Use modbusIsOk() and modbusGetGeneralError(). See Error handling.
Parsing requests	Use modbusParseRequestRTU() instead of modbusParseRequest(). Provide slave address and the request frame as arguments.
Register callback	Slave register callback now takes arguments in a struct. See Register callback.
Register/coil arrays	Write a register callback accessing your own array instead. See Register callback.
Register/coil write protection	Return exceptions from the register callback in response to R/W access check queries.
Accessing slave's response	Use modbusSlaveGetResponse() and modbusSlaveGetResponseLength() instead of directly accessing the fields in ModbusSlave.
Building requests	Use modbusBuildRequest*RTU() instead of modbusBuildRequest*().
Accessing master's request	Use modbusMasterGetRequest() and modbusMasterGetRequestLength() instead of directly accessing the fields in ModbusMaster.
Parsing responses	Use modbusParseResponseRTU() instead of modbusParseResponse(). Provide both request and response frames as arguments.
Receiving data	Implement a data callback to receive the data on the master end — see Data callback.
Endianness operations	Use modbusRLE(), modbusRBE(), modbusWLE() and modbusWBE().
Mask read/write	modbusMaskRead() and modbusMaskWrite() no longer provide bounds checking.
Static memory allocation	Implement a custom static memory allocator — see Static memory allocation.
User's context pointer	Use modbusMasterSetUserPointer(), modbusMasterGetUserPointer(), modbusSlaveSetUserPointer() and modbusSlaveGetUserPointer()
User's functions	Provide an array with all functions you want to be used to modbusSlaveInit() or modbusMasterInit()