Show error if config.json includes both googleAuth and refreshToken s…

…ections.

Fix periodic authentication issue in refreshToken mode.

Bump version to 4.6.1.

Clarifications on refresh token method.

1. Update Axios dependency version to 0.21.1.

2. Fix Homebridge 1.30/1.31 warnings.

Remove need for apiKey in configuration. Fix unable to control fan on…

… some thermostats. Fix low battery warning not appearing for Nest x Yale Lock. Fix plug-in crashing if started with incompletely-configured Nest devices in account.

Bump package.json versions, README.

- Support for new Google Nest Thermostat.

- Fix Home/Away sync issues.
- Fix temperature rounding issues (Thermostat/Temperature Sensors).

Additional fix for HomeKit vs. Nest app temperature rounding discrepa…

…ncy.

Fix for fan timer duration characteristic warning in Homebridge 1.3.0.