NOPCAVIZ  system property for disabling the visualization app
Cursor for uninitialized WaveformSource should start at -1.
Make stop() method safe even when start() was never called.
Added some comments about parameters that may need tuning for future scalability
Back to read in lieu of take; for subsequent iteration of the reader where needed.
Use implicit subscriber and publisher
Only start VitalModel and PumpModel for PCA or Visualization app.  Only start CapnoModel for the RRR app.
Important to only read NOT_READ samples
Don't render the entire waveformsource in the first render pass.