- testOneRegi runs are useful for fast development iterations ("do these
  changes break the model, or does it still run"), so setting them up
  should be fast as well

- supplying the parameter "--testOneRegi" to start.R will ignore any
  scenario_config file provided and modify the default configuration to
  start a testOneRegi run in the directory output/testOneRegi with no
  output processing
- the old oneRegi.R script and oneRegi.cfg configuration are deleted

- existing output/testOneRegi directories are overwritten