Doxysphinx

Fix

- **deps**: pyparsing dependency is added correctly now
- **doxygen**: solve pre-commit errors by whitespaces
- **doxygen**: fix errors in validator pytest
- **doxygen**: adapt optional settings for doxyfile and documentation

Fix

- **styling**: moved rtd style fixes to doxysphinx

Fix

- **doxygen**: fix warning for wrong outdir
- **doxygen**: correct the handling of relative paths and adjust pytests
- **doxygen**: add parser for doxygen config
- **validator**: fix small bug that broke build command
- **validator**: adapt error messages of validator
- **validator**: switch some settings to optional
- **doxygen**: merge current changes from global repo
- **doxygen**: respect include-tags in doxyfile

Fix

- **validator**: fix small bug that broke build command
- **validator**: adapt error messages of validator
- **validator**: switch some settings to optional

Fix

- **ci**: commit to bump version and force a release