Niklas

This PR adds support for - variable support via overwriting the `applyTemplateVariable` function of the class `DataSource`. - Now topics can contain variables. E.g.: `tlm/${Device}/measurement` - Single selection and all...

Add support to publish data via different query

5

This PR adds support to publish data via the datasource by sending a different payload. This can be used by plugins like [Buttons Panel](https://grafana.com/grafana/plugins/speakyourcode-button-panel/) or [Data Manipulation](https://grafana.com/grafana/plugins/volkovlabs-form-panel/). Publish timeouts after...

This PR checks if the `transport` is not nil before closing it in `client.Close()`. This avoid panics.