Mark Herwege

> I understand what you want to achieve, but why did you chose `HistoricItem` as return value? The timestamp has no meaning for averages or similar, a simple `State` would...

@J-N-K the methods now return State. As this is API breaking anyway, I also aligned method names. EvolutionRate whas the only group of methods that did not have a distinction...

> I have a rule that calculates the mean temperature over the last three days. It uses averageSince and then adds the unit before posting the update to the item....

> If this gets merged for 4.1, we should try to implement a solution for #3896 for 4.1 as well to avoid having multiple sets of breaking changes. @J-N-K @florian-h05...

> But why? I thought when the unit is properly set you can just post a unit with an empty value and the unit from the metadata will be assumed?...

> I agree that I want this change, I am just not sure when (before or after 4.1). I tend towards waiting after the release, so that we can get...

> What's the state here? Are the discussed extensions already included and we can review and merge? The sooner, the better: more time for testing. Sorry, not yet. And I...

@J-N-K, @florian-h05 I completed the work on persistence extensions, so this is now ready for review. I messed up my local git history, so had to force push a new...

> Sorry to be so late to the party. I would suggest calling the methods `Until` instead of `Till`. Fine for me, change done.

I am going through the javadocs again. Many of them need updates or clarifications. I am working on that and will come back with refinements on them.