Small cleaning
Added MET to the display

First version. The MET vector appears properly on the 3D view but not on
the projections... Why?
More objects available for display

Are shown: electron, muons, photons, genjets. For now, collections are hardcoded.
The MET issue in projection is still there.
Other items on the todo-list: better GUI controls, additional tabs with
full 3D geometry, summary, and plots.