Executing regression tests:

1. Individual
phenix.python path-to-regression-test-file <test|display|update>
    [ -e <script|python> ] [ -n ncpus ]

Executes regression test pointed by the path (in any current directory)
using an execution mode (default: python). 

Modes:
  - test. Runs test and compares results with expected values
  - display. Displays expected results
  - update. Runs test and overwrites expected results with current ones
  

2. Grouped
phaser.regression regression-group-name
    [ -n ncpus ] [ -o <terse|full|html|silent|normal> ] 

Executes a regression test group (in any current directory). All individual
tests are available as a respective group, and there are certain predefined
sets grouped by functionality/test data used. The job will be executed on all
existing execution modes. Available group names are listed with the -h option.