Reduce PidEconomizer jitter on reaching the target temperature

[climategadgets]

Relevant as of rev. 224da0bafb7f68c8c427f85f899ed9b6026ae3ac

Expected Behavior

When the indoor temperature reaches the target temperature, control system issues a signal consistent with the usual PID controller system behavior.

Actual Behavior

Due to math used, properties of this PID controller must be tuned in a totally different way; it's possible that desired behavior can't be reached at all.

Corrective Action

Change the math to be in line with the rest of the system to comply to the Principle of least astonishment.

Relevant Data

[climategadgets]

Fixed as of rev. a850da183feb56ef736df6f96883c147549cca77.