Reframe 2.4 release notes

API changes

Support for OS variable expansion in the variables field
Fixed environment loading: modules are loaded first and variables are set
afterwards
Default value of the use_multithreading field is now None, in which case
no hint is emitted

Brand new frontend
- Google Test look-and-feel
- Less verbose output
- Better error handling and management
- Better test statistics management
- Support for pluggable execution policies of regression tests
- New command line option --exec-policy for setting the execution policy of
  the regression tests
- Regression checks are not reused anymore across partitions and programming environments. Instead, they are cloned for every case.
Support for asynchronous execution of regression tests
- The running phase of regression tests is executed in parallel
- Support for different maximum pending jobs per partition
Full logging support
- Multiple logging levels
- Multiple log record handlers
- Easily configured in reframe/settings.py
- New command line option --save-log-files for saving the produced log files
  in the output directory of the run
More robust user check validation
- The regression test file is first parsed for the correct definition of the
  _get_checks() method and is then loaded and further validated