Rename member variables to follow convention of m_ prefix
In addition:
- Introduce pre-build checks in the CI to
- Check that clang-format has been applied to all files
- Check that the member variable naming convention is being followed in all classes
- Remove unused class EvtDecayParm
- Remove unused var from EvtXPsiGamma
- Fix some shadowing of variables
- Fixes to Doxygen configuration