Add Graphite support

[mchro]

Using the Graphite plaintext protocol: https://graphite.readthedocs.io/en/latest/feeding-carbon.html

I chosed some specific datapoints to grab out, to not send a lot of redundant data.

[daromer2]

Your code is static. It should be based on the message files and generic like sendinflux and mqtt is.

[mchro]

I think it makes little sense to blindly copy all the fields from the messages to Graphite. In Graphite every datapoint becomes a series (pre-allocated, etc.). Graphite has builtin support for a lot of data manipulation, so it e.g. does not make sense to store averages, minimum, or maximum, if the data points are available for calculating them.

I could hide selection of fields behind a config flag, so the option of doing the generic storing is there?

[daromer2]

The thing is the "case" that is extra in the code. To have this code as generic as possible to handle all scenarios i would like to skip them as far as we can. I know that graphite can work with the data and same does Influx. Not all messages from Batrium suit those databases since you get tons of em :)