modbus-server: improving test firmwares
modbus-server: added support for reading input registers
modbus-server: added support RTS pin; proper start/stop code
added support of ATmega8535 to usart0, timer1 drivers
added support of ATmega8535 to int0, int1 drivers
modbus-server: added USART init code
modbus-server: proof of concept
prototyping heating controller