Reduce API calls

[CFenner]

To get a full picture of a system, today each device needs to be updated on its own.

https://documentation.viessmann.com/installationgatewayfeatures-featuresapi-mw-iot/v2#installationgatewayfeatures-featuresapi-mw-iot_Get_gateway_features

https://api.viessmann.com/iot/v2/features/installations/
  {installationId}/gateways/
  {gatewaySerial}/features{?regex,filter,skipDisabled,includeDevicesFeatures}

includeDevicesFeatures
indicates whether return or not devices' features; if this is set to true, the disabled features will be filtered out

Maybe this endpoint could be used to fetch the data point for all devices of a gateway and therefore reduce the number of requests that are needed.