Added support for MODBUS RTU communiation (RS232 and RS485).
Additional configuration parameters (parity, data bits, stop bits) support for Modbus RTU. Multiple fixes.
Modbus RTU available only if libmodbus version >= 3.
Fixed (serial port) parameter handling and extended verbosity param for modbus debug (verbosity level >= 2).
Fixed formatting of code blocks.
Readme file fixes.
Updated ChangeLog and version information. (v0.4)