Keep dotted string, not vector, which makes name management much more lightweight.
Introduce typed strings, to distinguish full paths ("hist.line.color") from just the final element ("color").
Rename AsOption to FromOption, which is more meaningful when reading the invocation.

will fail in exp PyROOT

* Fix doxygen generation with Python 3

* Adjust tutorials for doxygen documentation generation.
When run inside the makeimage.py wrapper during doxygen generation the
variable scope is different than when the tutorials are run stand-alone.
The change in tutorials/math/tStudent.py is Python 3 specific and is due to
that list comprehensions in Python 3 are run in an implicit function scope.

to avoid confusion and to allow to instantiate the templates of
both free functions and use them in fully compiled DFs.

therewith making them standalone.

this commit suggests to prefer the usage of ROOT::Math::TLorentzVector
specialisations instead of the TLorentzVector class given the
advantages of the former.
- Release notes are changes
- The documentation of TLorentzVector updated to point to the specialisations of ROOT::Math::TLorentzVector
- The RDF tutorials using TLorentzVector upgraded

in order to make of this code the most up-to-date set of examples possible.

Tested with 6.16/00