push 5

- replaced joystick with buttons to increase thermostat setting.
- Added functionality to display the desired temperature on two
7-segment LEDs.
- introduced USART communication between door and thermostat.
- added LED array which displays current room temp.
- Added buttons to emulate thermometer reading of the room.
- Added functionality where the thermostat uC will correct room
temperature if it exceeds or falls below the desired temperature.
- Added two LEDs which indicate whether the AC or heater are on.
- Thermostat uC sends flag to the door uC to indicate whether the AC or
the heater is on. The uC (usually) displays a message indicating which
actuator is on.

pretty much done :)