Merge branch 'feature-fixed_values' into 'develop'
Feature fixed values See #126 Order of prio of config values: 1. Fixed values 2. User config (-config / -cv on the command line) 3. Default files (coming from BIOPET_CONFIG env) 4. Default values inside the code. Also changed way to use default values. No need for a merge step anymore, this happens inside the class now. This makes code inside pipelines/extensions cleaner. Todo: - [x] Basic implementation - [x] Unit testing See merge request !233