Change tabs to spaces.
drop suggestion of contao-community-alliance/dependency-container-inspector.
Activate ccabs.
Fix code style issues.
Reduce cyclomatic complexity.
Add provisioning of base Contao singletons.
Bump version.
Merge branch 'release/1.6.0-alpha1'
Merge tag '1.6.0-alpha1' into develop

Version 1.6.0-alpha1