account for NodeOutput possibly not being initialized when Context is started, happens when no Node's are directly connected to it.
added beginning of InputAnalyzer sample
added CI_VERIFY / CI_VERIFY_MSG macros
added CI_ASSERT_NOT_REACHABLE() macro
minor formatting
added optional border to SpectrumPlot
added ScopeSpectral::getFreqForBin(), getNumBins(), docs. Cleanup test app
added info to explain what the SpectrumPlot / mag spectrum is showing