Nice!

It leaves the impression of an elaborate and well structured library. The getting started document was a good idea, too.

I didn't have a deeper look into it yet, though. I certainly will just as I need it.

BTW: The issue of having to pass at least one parameter when calling struct methods seems to be fixed in A8. At least the compiler doesn't like _observer->callback(0) etc. and won't do its job anymore. In A7 it compiles fine.