Integrate with SampledSignals.jl?

[Keno]

https://github.com/JuliaAudio/SampledSignals.jl

Would be good to asses whether this is a worthwhile integration.

[mbaz]

I remember reading somewhere (discourse?) that SampledSignals was basically stagnant and in need of a re-write, but I can't find that message now. It would be a good idea to get up to speed on the state of the various related packages.

[sjkelly]

I did a quick audit. Conceptually it is mostly similar, though we have some differences in abstraction. One thing I am keen on is giving us windows into controlling and introspecting latency, which should be addressed in #22. This does not seem to be handled in SampledSignals. This means keeping around time stamps and such. I also am doing a minor rework today to make sure we can handle CuArray and others without copy, something also missing there. EDIT: This doesn't work.

Though I generally think these types of software<->hardware interfaces could use a common abstraction. These things are no longer simple serial port IO. May be good to roll with what we have for now and bring some minds together to work on a common spec in the future. Maybe similar in spirit to the FileIO organization.

[sjkelly]

On a more cursory audit I think SampledSignals is really good for the SDR use case (with some massaging, which should be pretty easy to SoapySampleSource <: AbstractSampleSource). Though I do think what we have here is mostly sufficient. I generally worry about dependency/scope creep. This is "Julia Wrappers for SoapySDR", and I think we are already few more rungs up the abstraction ladder here than we should be already. Maybe we look to back-ending SoapySDR to AbstractSDRand do more high level work with SampledSignals there?

cc @RGerzaguet