change names, add comment, improve return type to avoid extra call to get EngineControl::State*
prevent key press in pre-main-window dialog(s) from crashing the program because there is no editor window to forward key presses to
reinstate unblocking-of-connections in session setup, accidentally dropped in reorganization work
lots of changes to auto-start (and stop) the backend for latency measurements, and continuing work on the session construction/engine configuration flow