Renaming HA entity IDs

[proddy]

    So I bit the bullet. This is what I did:

1. Create a rename script for the database entries (let me know if you're interested).
2. Modified EMS-ESP to not use MQTT (actually, I routed it to a test broker).
3. In the MQTT broker, I removed all autodiscovery items for EMS-ESP.
4. In HA, removed the EMS-ESP, boiler and thermostat from the MQTT integration.
5. Run the rename sql to update all database entries.
6. Reflashed the gateway with v3.5b11.
7. Re-attached to the boiler and verify it is working.
8. Modify EMS-ESP to use the real MQTT broker and enable autodiscovery.
9. Hunt down YAML files and change entity names.

Maybe some of the steps are unneccessary, but this worked for me.
Unfortunately, due to a recent change in HA the 'more info' popup will only show new data. 'show more' will show all data.

Originally posted by @sciurius in #804 (comment)