Always determine virtual run time wrt job local start time:
Always determine virtual run time wrt job local start time:

* previous behaviour, whilst it makes sense when multiple jobs are running
  and interacting, was potentially confusing in the current use-case of
  code, run, stop, code, run, stop...

* revisit this behaviour in version 3.0 when we make more of a focus on
  live coding
jweather/sonic-pi,jweather/sonic-pi,jweather/sonic-pi,jweather/sonic-pi,jweather/sonic-pi