Completed creation of mess form factor that supports polarized calculations; refactor: remove spaces before public, protected, private

- 3rd person form: "Does" this or that.
- For all const methods that return something: "Returns" ...
- For boolean return value: "Returns true if " ...

manual editing of @brief ("defines ...", "implements ..."), removed multiple white lines

Refactored decorator classes, added Experiment, Beam and Detector classes and added prototype pattern to many classes (clone() function)