Misleading docstring and type hints in beam class methods

[Hespe]

The docstrings, parameter names and type hints of some beam class methods are not consistent with the new coordinate system. In particular, the from_twiss() method refers to sigma_s and its docstrings for sigma_p disagrees with from_parameters() about its unit.

Furthermore, the num_particles parameter of ParticleBeam methods is supposed to be a torch.Tensor according to its type hint, but the methods crash if a tensor is provided and a standard integer works.