Sync and display humidity setpoint

Migrating from:


This configuration populates zoneHumidityLow with a constant value of 36.

Frost control seems to do the same thing, just changes the value in zoneHumidityLow.

Checking this on another user also shows humidity in the zoneHumidityLow field.

For dehumidifiers zoneHumidityHigh seems to be the value.

Note to self: When doing this migration, do #250 at the same time.