Renaming the SDK

[alex-lotz]

The name SeRoNetSDK is very generic and it is not clear what it represents. In my opinion, something like "SeRoNet OPC UA Backend" (or any combination of these keywords) would summarize a lot better the content of this SDK. This is not a pressing issue, but I'd like to start a conversation and maybe at some point trigger a renaming (when it is not disturbing any current scenarios).