Unable to change back to scheduled temperature (auto mode) #24

Description

When changing to thermostat mode to ECO, there is no way to going back to the scheduled temperature.

Steps to reproduce

1. A thermostat is in automatic mode following the weekly schedule at 22 degrees.
2. We enable the eco mode calling set_temperature_mode(device, 14.0, MAX_DEVICE_MODE_MANUAL)
3. We return to auto mode calling set_mode(device, MAX_DEVICE_MODE_AUTOMATIC)
4. The temperature should be back to 22 degrees but instead is keep at ECO temperature (14 degrees) until next scheduled change.