Implementing preset modes - Manual, Scheduled and Vacation

[mihtjel]

The Danfoss Eco2 thermostats offer 4 different modes: Manual, Scheduled, Vacation - and Hold, which puts it in frost protection mode. This mode is not normally available from the app that I know of, but it does work fine with it.

This PR adds the ability to control the first 3 modes through MQTT, and I have tried it out using Home Asisstant.

It also has a few corrections in spelling and naming where I had happened across them.

I had not managed to get the tests running locally, so those have not been modified. I have tested in a live environment instead :-)