Add ability to tag objects as types, and display kinematics in separate windows

[EdwardMoyse]

This is really for masterclasses, and so we would have to think about how best to implement this

But the idea would be that you could select track and assign them to calo clusters, tagging them as (1) electron/positron , (2) muon/anti-muon, (3) photon

Students should select pairs of particles, and the window should calculate the invariant mass and show it in a table (in a separate window)

This table then should be possible to export into plain text with two columns: event type (e: 2 electrons, m: 2 muons, g: 2 photons, 4e: 4 electrons, 2e2m: 2 electrons and 2 muons and 4m: 4 muons), and invariant mass.

[remo-lab]

@EdwardMoyse , I would like to work on this issue.